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Careful dietary management that reduces high phosphate intake is recommended to slow the progression of chronic kidney disease (CKD) and prevent complications of CKD and may help reduce chronic disease risks such as incident CKD associated with high phosphate intake in the healthy general population. For patients treated with maintenance dialysis, control of serum phosphorus levels is considered a marker of good care and requires a coordinated plan that limits dietary phosphate intake, uses oral phosphate binders, and provides an adequate dialysis prescription. Even with traditional thrice-weekly hemodialysis or peritoneal dialysis, use of phosphate binders, and a concerted effort to limit dietary phosphate intake, adequately controlled serum phosphorus levels are not possible in all dialysis patients. Efforts to limit phosphate intake are thwarted by the underestimated and unquantified phosphate content of processed foods and some medications due to the hidden presence of phosphate additives or excipients added during processing or drug formulation. Effectively limiting phosphate intake could potentially be achieved through simple US Food and Drug Administration regulatory actions. Mandatory labeling of phosphate content on all packaged foods and drugs would enable identification of healthy low-phosphate foods and medications and permit critically important control of total phosphate intake. Simple changes in regulatory policy and labeling are warranted and would enable better management of dietary intake of phosphate at all stages of kidney disease, as well as potentially reduced health risks in the general population., (Copyright © 2018 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Medicare costs for phosphate binders for US dialysis patients and patients with chronic kidney disease enrolled in Medicare Part D exceeded $1.5 billion in 2015. Previous data have shown that Part D costs for mineral and bone disorder medications increased faster than costs for all Part D medications for dialysis patients. Despite extensive use of phosphate binders and escalating costs, conclusive evidence is lacking that they improve important clinical end points in dialysis patients or non-dialysis-dependent patients with chronic kidney disease. Using dialysis patient data from the US Renal Data System and laboratory information from the Centers for Medicare & Medicaid Services (CMS) CROWNWeb data, we update information on trends in phosphate-binder use, calcium and phosphorus values, and costs for Medicare-covered dialysis patients. We discuss these results in the context of evidence from clinical trials, meta-analyses, and observational studies evaluating phosphate-binder efficacy, safety, comparative effectiveness, and cost-effectiveness. Based on our analysis, we note a need for US Food and Drug Administration guidance regarding clinical evaluation of new phosphate binders, and we suggest that it would be in CMS' best interest to fund a clinical trial to assess whether lower versus higher phosphate concentrations improve hard clinical outcomes, and if so, whether particular phosphate binders are superior to placebo or other binders in improving these outcomes., (Copyright © 2017 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Vascular calcification is common among patients with chronic kidney disease (CKD), and it is associated with all-cause and cardiovascular disease mortality. Deoxycholic acid, a metabolite of circulating bile acids, is elevated in CKD and induces vascular mineralization and osteogenic differentiation in animal models., Study Design: Cohort analysis of clinical trial participants., Setting & Participants: 112 patients with moderate to severe CKD (estimated glomerular filtration rate, 20-45mL/min/1.73m 2 ) who participated in a randomized controlled study to examine the effects of phosphate binders on vascular calcification., Predictor: Serum deoxycholic acid concentration., Outcomes: Baseline coronary artery calcification (CAC) volume score and bone mineral density (BMD) and change in CAC volume score and BMD after 9 months., Measurements: Deoxycholic acid was assayed in stored baseline serum samples using liquid chromatography-tandem mass spectrometry, CAC was measured using a GE-Imitron C150 scanner, and BMD was determined using computed tomographic scans of the abdomen with calibrated phantom of known density., Results: Higher serum deoxycholic acid concentrations were significantly correlated with greater baseline CAC volume and lower baseline BMD. After adjusting for demographics, coexisting illness, body mass index, estimated glomerular filtration rate, and concentrations of circulating markers of mineral metabolism, including serum calcium, phosphorus, vitamin D, parathyroid hormone, and fibroblast growth factor 23, a serum deoxycholic acid concentration > 58ng/mL (the median) was positively associated with baseline CAC volume (β=0.71; 95% CI, 0.26-1.16; P=0.003) and negatively associated with baseline BMD (β = -20.3; 95% CI, -1.5 to -39.1; P=0.04). Serum deoxycholic acid concentration > 58ng/mL was not significantly associated with change in CAC volume score after 9 months (β=0.06; 95% CI, -0.09 to 0.21; P=0.4). The analysis for the relationship between baseline deoxycholic acid concentrations and change in BMD after 9 months was not statistically significant, but was underpowered., Limitations: The use of nonfasting serum samples is a limitation because deoxycholic acid concentrations may vary based on time of day and dietary intake. Few trial participants with complete data to evaluate the change in CAC volume score (n=75) and BMD (n=59). No data for changes in deoxycholic acid concentrations over time., Conclusions: Among patients with moderate to severe CKD, higher serum deoxycholic acid concentrations were independently associated with greater baseline CAC volume score and lower baseline BMD., (Published by Elsevier Inc.)

Background: The kidneys maintain acid-base homeostasis through excretion of acid as either ammonium or as titratable acids that primarily use phosphate as a buffer. In chronic kidney disease (CKD), ammoniagenesis is impaired, promoting metabolic acidosis. Metabolic acidosis stimulates phosphaturic hormones, parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF-23) in vitro, possibly to increase urine titratable acid buffers, but this has not been confirmed in humans. We hypothesized that higher acid load and acidosis would associate with altered phosphorus homeostasis, including higher urinary phosphorus excretion and serum PTH and FGF-23., Study Design: Cross-sectional., Setting & Participants: 980 participants with CKD enrolled in the Chronic Renal Insufficiency Cohort (CRIC) Study., Predictors: Net acid excretion as measured in 24-hour urine, potential renal acid load (PRAL) estimated from food frequency questionnaire responses, and serum bicarbonate concentration < 22 mEq/L., Outcome & Measurements: 24-hour urine phosphorus and calcium excretion and serum phosphorus, FGF-23, and PTH concentrations., Results: Using linear and log-linear regression adjusted for demographics, kidney function, comorbid conditions, body mass index, diuretic use, and 24-hour urine creatinine excretion, we found that 24-hour urine phosphorus excretion was higher at higher net acid excretion, higher PRAL, and lower serum bicarbonate concentration (each P<0.05). Serum phosphorus concentration was also higher with higher net acid excretion and lower serum bicarbonate concentration (each P=0.001). Only higher net acid excretion associated with higher 24-hour urine calcium excretion (P<0.001). Neither net acid excretion nor PRAL was associated with FGF-23 or PTH concentrations. PTH, but not FGF-23, concentration (P=0.2) was 26% (95% CI, 13%-40%) higher in participants with a serum bicarbonate concentration <22 versus ≥22 mEq/L (P<0.001). Primary results were similar if stratified by estimated glomerular filtration rate categories or adjusted for iothalamate glomerular filtration rate (n=359), total energy intake, dietary phosphorus, or urine urea nitrogen excretion, when available., Limitations: Possible residual confounding by kidney function or nutrition; urine phosphorus excretion was included in calculation of the titratable acid component of net acid excretion., Conclusions: In CKD, higher acid load and acidosis associate independently with increased circulating phosphorus concentration and augmented phosphaturia, but not consistently with FGF-23 or PTH concentrations. This may be an adaptation that increases titratable acid excretion and thus helps maintain acid-base homeostasis in CKD. Understanding whether administration of base can lower phosphorus concentrations requires testing in interventional trials., (Copyright © 2017 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Mild hyperphosphatemia is a putative risk factor for cardiovascular disease [CVD], loss of kidney function, and mortality. Very limited data are available from sizable multicenter kidney transplant recipient (KTR) cohorts assessing the potential relationships between serum phosphorus levels and the development of CVD outcomes, transplant failure, or all-cause mortality., Study Design: Cohort study., Setting & Participants: The Folic Acid for Vascular Outcome Reduction in Transplantation (FAVORIT) Trial, a large, multicenter, multiethnic, controlled clinical trial that provided definitive evidence that high-dose vitamin B-based lowering of plasma homocysteine levels did not reduce CVD events, transplant failure, or total mortality in stable KTRs., Predictor: Serum phosphorus levels were determined in 3,138 FAVORIT trial participants at randomization., Results: During a median follow-up of 4.0 years, the cohort had 436 CVD events, 238 transplant failures, and 348 deaths. Proportional hazards modeling revealed that each 1-mg/dL higher serum phosphorus level was not associated with a significant increase in CVD risk (HR, 1.06; 95% CI, 0.92-1.22), but increased transplant failure (HR, 1.36; 95% CI, 1.15-1.62) and total mortality risk associations (HR, 1.21; 95% CI, 1.04-1.40) when adjusted for treatment allocation, traditional CVD risk factors, kidney measures, type of kidney transplant, transplant vintage, and use of calcineurin inhibitors, steroids, or lipid-lowering drugs. These associations were strengthened in models without kidney measures: CVD (HR, 1.14; 95% CI, 1.00-1.31), transplant failure (HR, 1.72; 95% CI, 1.46-2.01), and mortality (HR, 1.34; 95% CI, 1.15-1.54)., Limitations: We lacked data for concentrations of parathyroid hormone, fibroblast growth factor 23, or vitamin D metabolites., Conclusions: Serum phosphorus level is marginally associated with CVD and more strongly associated with transplant failure and total mortality in long-term KTRs. A randomized controlled clinical trial in KTRs that assesses the potential impact of phosphorus-lowering therapy on these hard outcomes may be warranted., (Copyright © 2017 National Kidney Foundation, Inc. All rights reserved.)

Background: High serum phosphorus levels are associated with cardiovascular morbidity and mortality in kidney disease. Although serum phosphorus levels possibly influence on mortality in individuals without kidney disease, this is uncertain because of the variable sex- and age-based distribution of serum phosphorus levels., Study Design: Observational cohort study., Setting & Participants: Clinical and biochemical data were collected from 138,735 adults undergoing routine health checkups in 3 tertiary hospitals. Individuals with estimated glomerular filtration rates < 60 mL/min/1.73 m2 and urine dipstick albumin ≥ 1+ were excluded., Predictor: Sex-specific quartiles of serum phosphorus and sex., Outcomes: All-cause mortality., Results: The study included 92,756 individuals. Generally, women showed higher serum phosphorus levels than men. In women, serum phosphorus levels increased with age until 60 years old, then decreased with age. Men with higher serum phosphorus levels were younger and less likely to have hypertension, whereas women with higher serum phosphorus levels were older and more likely to have diabetes and hypertension. During a median follow-up of 75 months, 1,646 participants died. In the overall population, higher serum phosphorus levels were an independent predictor for all-cause mortality after adjustment (adjusted HR for the highest vs. lowest quartile, 1.34; 95% CI, 1.15-1.56; P<0.001). We observed that this increased risk was present in men but not in women (adjusted HR of 1.43 [95% CI, 1.22-1.68] vs. 1.01 [95% CI, 0.76-1.33]), but interaction by sex was not significant (P=0.8)., Limitations: A single phosphorus measurement and low power to test for interactions by sex and age., Conclusions: We demonstrated that higher serum phosphorus levels influenced all-cause mortality in individuals with normal kidney function. Our findings suggest that the association may differ by sex, but future studies with adequate power to test for effect modification are needed to confirm our findings., (Copyright © 2016 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Serum parathyroid hormone (PTH), phosphorus, and calcium levels are surrogate outcomes that are central to the evaluation of drug treatments in chronic kidney disease (CKD). This systematic review evaluates the evidence for the correlation between drug effects on biochemical (PTH, phosphorus, and calcium) and all-cause and cardiovascular mortality end points in adults with CKD., Study Design: Systematic review and meta-analysis., Setting & Population: Adults with CKD., Selection Criteria for Studies: Randomized trials reporting drug effects on biochemical and mortality end points., Intervention: Drug interventions with effects on serum PTH, phosphorus, and calcium levels, including vitamin D compounds, phosphate binders, cinacalcet, bisphosphonates, and calcitonin., Outcomes: Correlation between drug effects on biochemical and all-cause and cardiovascular mortality., Results: 28 studies (6,999 participants) reported both biochemical and mortality outcomes and were eligible for analysis. Associations between drug effects on surrogate biochemical end points and corresponding effects on mortality were weak and imprecise. All correlation coefficients were less than 0.70, and 95% credible intervals were generally wide and overlapped with zero, consistent with the possibility of no association. The exception was an inverse correlation between drug effects on serum PTH levels and all-cause mortality, which was nominally significant (-0.64; 95% credible interval, -0.85 to -0.15), but the strength of this association was very imprecise. Risk of bias within available trials was generally high, further reducing confidence in the summary correlations. Findings were robust to adjustment for age, baseline serum PTH level, allocation concealment, CKD stage, and drug class., Limitations: Low power in analyses and combining evidence from many different drug comparisons with incomplete data across studies., Conclusions: Drug effects on serum PTH, phosphorus, and calcium levels are weakly and imprecisely correlated with all-cause and cardiovascular death in the setting of CKD. Risks of mortality (patient-level outcome) cannot be inferred from treatment-induced changes in biochemical outcomes in people with CKD. Similarly, existing data do not exclude a mortality benefit with treatment. Trials need to address patient-centered outcomes to evaluate drug effectiveness in this setting., (Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Recent studies have indicated that phosphorus may play an independent pathogenic role in chronic kidney disease (CKD) progression, but some of those studies were underpowered and yielded inconsistent results., Study Design: Systematic review and meta-analysis., Setting & Population: Non-dialysis-dependent patients with CKD (transplant recipients were excluded)., Selection Criteria for Studies: Studies assessing the risk ratio of serum phosphorus level on kidney failure and mortality for non-dialysis-dependent patients with CKD published from January 1950 to June 2014 were included following systematic searching of MEDLINE, EMBASE, and the Cochrane Library., Predictor: Serum phosphorus level., Outcome: Kidney failure, defined as doubled serum creatinine level, 50% decline in estimated glomerular filtration rate, or end-stage kidney disease., Results: In 12 cohort studies with 25,546 patients, 1,442 (8.8%) developed kidney failure and 3,089 (13.6%) died. Overall, every 1-mg/dL increase in serum phosphorus level was associated independently with increased risk of kidney failure (hazard ratio, 1.36; 95% CI, 1.20-1.55) and mortality (hazard ratio, 1.20; 95% CI, 1.05-1.37)., Limitations: Existence of potential residual confounding could not be excluded., Conclusions: This meta-analysis suggests an independent association between serum phosphorus level and kidney failure and mortality among non-dialysis-dependent patients with CKD and suggests that large-scale randomized controlled trials should target disordered phosphorus homeostasis in CKD., (Copyright © 2015 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Background: There have been few prospective controlled studies of kidney donors. Understanding the pathophysiologic effects of kidney donation is important for judging donor safety and improving our understanding of the consequences of reduced kidney function in chronic kidney disease., Study Design: Prospective, controlled, observational cohort study., Setting & Participants: 3-year follow-up of kidney donors and paired controls suitable for donation at their donor's center., Predictor: Kidney donation., Outcomes: Medical history, vital signs, glomerular filtration rate, and other measurements at 6, 12, 24, and 36 months after donation., Results: At 36 months, 182 of 203 (89.7%) original donors and 173 of 201 (86.1%) original controls continue to participate in follow-up visits. The linear slope of the glomerular filtration rate measured by plasma iohexol clearance declined 0.36±7.55mL/min per year in 194 controls, but increased 1.47±5.02mL/min per year in 198 donors (P=0.005) between 6 and 36 months. Blood pressure was not different between donors and controls at any visit, and at 36 months, all 24-hour ambulatory blood pressure parameters were similar in 126 controls and 135 donors (mean systolic blood pressure, 120.0±11.2 [SD] vs 120.7±9.7mmHg [P=0.6]; mean diastolic blood pressure, 73.4±7.0 vs 74.5±6.5mmHg [P=0.2]). Mean arterial pressure nocturnal dipping was manifest in 11.2% ± 6.6% of controls and 11.3% ± 6.1% of donors (P=0.9). Urinary protein-creatinine and albumin-creatinine ratios were not increased in donors compared with controls. From 6 to 36 months postdonation, serum parathyroid hormone, uric acid, homocysteine, and potassium levels were higher, whereas hemoglobin levels were lower, in donors compared with controls., Limitations: Possible bias resulting from an inability to select controls screened to be as healthy as donors, short follow-up duration, and dropouts., Conclusions: Kidney donors manifest several of the findings of mild chronic kidney disease. However, at 36 months after donation, kidney function continues to improve in donors, whereas controls have expected age-related declines in function., (Copyright © 2015 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Serum phosphorus levels have been associated with mortality in some but not all studies. Because dietary intake prior to measurement can affect serum phosphorus levels, we hypothesized that the association between serum phosphorus level and mortality is strongest in those who have fasted longer., Study Design: Prospective cohort study., Setting & Participants: Nationally representative sample of 12,984 participants 20 years or older in the Third National Health and Nutrition Examination Survey (1988-1994)., Factors: Serum phosphorus level, fasting duration (dichotomized as ≥ 12 or < 12 hours)., Outcomes: All-cause and cardiovascular mortality determined by death certificate data from the National Death Index., Measurements: Serum phosphorus measured in a central laboratory and fasting duration recorded as time since food or drink other than water was consumed., Results: Individuals fasting 12 or more hours had lower serum phosphorus levels than those fasting less than 12 hours (3.34 vs 3.55 mg/dL; P < 0.001) and higher correlation with repeat measurement (0.66 vs 0.53; P = 0.002). In multivariable-adjusted Cox regression models, the highest quartile of serum phosphorus was associated with increased mortality in participants fasting 12 or more hours (adjusted HR, 1.74; 95% CI, 1.38-2.20; reference, lowest quartile) but not in participants fasting less than 12 hours (adjusted HR, 1.08; 95% CI, 0.89-1.32; P for interaction = 0.002). Relationships were consistent using 8 hours as the fasting cutoff point or cardiovascular mortality as the outcome., Limitations: Observational study, lack of fibroblast growth factor 23 or intact parathyroid hormone measurements., Conclusions: Fasting but not nonfasting serum phosphorus levels were associated with increased mortality. Risk prognostication based on serum phosphorus may be improved using fasting levels., (Copyright © 2014 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Elevated serum phosphorus levels are common in patients with chronic kidney disease and are associated with heart and vascular disease, conditions that in turn are associated with increased mortality. Accurately managing phosphorus intake by restricting dietary protein alone can prove challenging because protein from different sources can contain varying amounts of available phosphorus. Additives used in processed foods frequently are high in inorganic phosphorus, which is readily absorbed, compounding this difficulty. Recent evidence suggests that dietary protein restriction in some cases may do more harm than good in some patients treated with maintenance hemodialysis because protein restriction can lead to protein-energy wasting, which is associated with increased mortality. Accordingly, phosphorus binders are important for managing hyperphosphatemia in dialysis patients. Managing hyperphosphatemia in patients with late-stage chronic kidney disease requires an individualized approach, involving a combination of adequate dietary advice, phosphate-binder use, and adjustments to dialysis prescription. We speculate that increased use of phosphate binders could allow patients to eat more protein-rich foods and that communicating this to patients might increase their perception of their need for phosphate binders, providing an incentive to improve adherence. The aim of this review is to discuss the challenges involved in maintaining adequate nutrition while controlling phosphorus levels in patients on maintenance hemodialysis therapy., (Copyright © 2014 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Hemodialysis patients with mineral and bone disorders (MBDs) have an abnormally high relative risk of death, but their absolute risk of death is unknown. Further, previous studies have not accounted for possible time-dependent confounding of the association between MBD markers and death due to the effect of markers of MBD on treatments, which subsequently may affect MBD markers., Study Design: Multicenter, 3-year, prospective, case-cohort study., Setting & Participants: 8,229 hemodialysis patients with secondary hyperparathyroidism (parathyroid hormone level ≥180 pg/mL and/or receiving vitamin D receptor activators) at 86 facilities in Japan., Predictors: Serum phosphorus, calcium, and parathyroid hormone levels., Outcome: All-cause mortality., Measurements: Marginal structural models were used to compute absolute differences in all-cause mortality associated with different levels of predictors while accounting for time-dependent confounding., Results: The association between phosphorus level and mortality appeared U-shaped, although only higher phosphorus level categories reached statistical significance: compared to those with phosphorus levels of 5.0-5.9 mg/dL (1.61-1.93 mmol/L), patients with the highest (≥9.0 mg/dL [≥2.90 mmol/L]) phosphorus levels had 9.4 excess deaths/100 person-years (rate ratio, 2.79 [95% CI, 1.26-6.15]), whereas no association was found for the lowest phosphorus category (<3.0 mg/dL [<0.97 mmol/L]; rate ratio, 1.54 [95% CI, 0.87-2.71]). Similarly, hypercalcemia (≥10.0 mg/dL [≥2.50 mmol/L]) was associated with excess deaths, and the highest level of hypercalcemia (≥11.0 mg/dL [≥2.75 mmol/L]) was associated with 5.8 excess deaths/100 person-years (rate ratio, 2.38 [95% CI, 1.77-3.21]) compared to those with levels of 9.0-9.4 mg/dL (2.25-2.37 mmol/L). Abnormally high parathyroid hormone levels were not associated with excess deaths., Limitations: Possible residual confounding., Conclusions: These results reinforce the idea that serum calcium (in addition to phosphorus) level is an important predictor of the absolute risk of death in hemodialysis patients with secondary hyperparathyroidism., (Copyright © 2014 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Elevation of serum phosphorus concentrations has been associated with cardiovascular events in older women and men. Whether age, sex, or estrogen therapy is associated with different phosphorus levels is unknown., Study Design: Cross-sectional study., Setting & Participants: 7,005 participants in the National Health and Nutrition Examination Survey (NHANES) 2003-2006., Predictors: Demographic data; body measurement indexes; dietary intake by 24-hour dietary recall and food-frequency questionnaire; data for reproductive health, prescription medication, cardiovascular disease, osteoporosis, and diabetes mellitus obtained by questionnaire; and blood chemistry indexes., Outcomes & Measurements: Serum phosphorus concentrations., Results: In both males and premenopausal females, serum phosphorus levels decline progressively with age. In males, the decline continues over the entire age range of 21-85 years. In contrast, in females, serum phosphorus levels increase between ages 46-60 years (sex×age interaction; P<0.001). The increase in serum phosphorus levels in older women is independent of changes in serum parathyroid hormone levels, daily dietary phosphorus intake, and estimated glomerular filtration rate. In analysis of covariance, we show that postmenopausal women receiving estrogen therapy have significantly lower serum phosphorus levels than non-estrogen users after adjusting for age, race, body mass index, daily dietary phosphorus intake, and serum albumin, serum parathyroid hormone, and 25-hydroxyvitamin D levels (3.83 vs 3.98mg/dL; P<0.001)., Limitations: The study was cross-sectional in design and estrogen therapy was not randomly assigned or concealed. Important phosphorus regulatory factors such as serum fibroblast growth factor 23 and klotho were not available in the study., Conclusions: Estrogen status may account for the difference in serum phosphorus levels in postmenopausal women., (Copyright © 2014 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Most dialysis patients require phosphate binders to control hyperphosphatemia. Ferric citrate has been tested in phase 2 trials as a phosphate binder. This trial was designed as a dose-response and efficacy trial., Study Design: Prospective, phase 3, multicenter, open-label, randomized clinical trial., Setting & Participants: 151 participants with hyperphosphatemia on maintenance hemodialysis therapy., Intervention: Fixed dose of ferric citrate taken orally as a phosphate binder for up to 28 days (1, 6, or 8 g/d in 51, 52, and 48 participants, respectively)., Outcomes: Primary outcome is dose-response of ferric citrate on serum phosphorus level; secondary outcomes are safety and tolerability., Measurements: Serum chemistry tests including phosphorus, safety data., Results: 151 participants received at least one dose of ferric citrate. Mean baseline phosphorus levels were 7.3 ± 1.7 (SD) mg/dL in the 1-g/d group, 7.6 ± 1.7 mg/dL in the 6-g/d group, and 7.5 ± 1.6 mg/dL in the 8-g/d group. Phosphorus levels decreased in a dose-dependent manner (mean change at end of treatment, -0.1 ± 1.3 mg/dL in the 1-g/d group, -1.9 ± 1.7 mg/dL in the 6-g/d group, and -2.1 ± 2.0 mg/dL in the 8-g/d group). The mean difference in reduction in phosphorus levels between the 6- and 1-g/d groups was 1.3 mg/dL (95% CI, 0.69 to 1.9; P < 0.001), between the 8- and 1-g/d groups was 1.5 mg/dL (95% CI, 0.86 to 2.1; P < 0.001), and between the 8- and 6-g/d groups was 0.21 mg/dL (95% CI, -0.39 to 0.81; P = 0.5). The most common adverse event was stool discoloration., Limitations: Sample size and duration confirm efficacy, but limit our ability to confirm safety., Conclusions: Ferric citrate is efficacious as a phosphate binder in a dose-dependent manner. A phase 3 trial is ongoing to confirm safety and efficacy., (Copyright © 2013 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Serum phosphorus is associated with cardiovascular disease (CVD) in the general population, but may not comprehensively reflect phosphorus homeostasis. Whether urine phosphorus-creatinine ratio (a marker of intestinal absorption) or urine fractional excretion of phosphorus (FEPi; a marker of urinary phosphorus handling) is associated with risk of mortality or CVD is uncertain., Study Design: Prospective observational study., Setting & Participants: 1,325 community-dwelling men 65 years or older participating in the MrOS Study., Predictor: Serum phosphorus, urine phosphorus-creatinine ratio, and FEPi., Outcomes: All-cause and CVD death., Results: Mean age was 74 ± 6 (SD) years, estimated glomerular filtration rate was 75 ± 16 mL/min/1.73 m(2), and serum phosphorus level was 3.2 ± 0.4 mg/dL. During a median follow-up of 9.3 years, there were 364 (120 CVD) deaths. After adjustment for demographics, CVD risk factors, and kidney function, the risks of all-cause death in the highest quartiles of serum phosphorus (≥3.6 mg/dL), urine phosphorus-creatinine ratio (≥0.55), and FEPi (≥18%) were 1.63 (95% CI, 1.23-2.17), 1.22 (95% CI, 0.90-1.65), and 0.88 (95% CI, 0.64-1.23), respectively, compared to the lowest quartiles of each. Results were similar for CVD death. Results also were similar in those with estimated glomerular filtration rate ≥60 and <60 mL/min/1.73 m(2)., Limitations: Older all-male cohort. Few had advanced chronic kidney disease. Spot urine specimens were used., Conclusions: In community-living older men, higher serum phosphorus concentrations are associated with all-cause and CVD death. In contrast, urine phosphorus-creatinine ratio and FEPi are not. These findings do not support using urine phosphorus-creatinine ratio or FEPi as adjuvant measures to predict risk of mortality or CVD in the general population., (Published by Elsevier Inc.)

Vascular calcification is associated with significant cardiovascular morbidity and mortality in patients with chronic kidney disease (CKD). Factors unique to patients with CKD, such as hyperphosphatemia, predispose these patients to early and progressive vascular calcification. Hyperphosphatemia appears to be involved in a number of mechanisms that trigger and advance the progression of vascular calcification, including (1) transition of vascular smooth muscle cells (VSMCs) from a contractile to an osteochondrogenic phenotype and mineralization of VSMC matrix through sodium-dependent phosphate cotransporters, (2) induction of VSMC apoptosis, (3) inhibition of monocyte/macrophage differentiation into osteoclast-like cells, (4) elevation of fibroblast growth factor 23 levels, and (5) decreases in klotho expression. Whether vascular calcification can be prevented or reversed with strategies aimed at maintaining phosphate homeostasis presently is unknown. This review discusses these mechanisms in depth, exploring the interplay among vascular calcification promoters, inhibitors, and substrate that affect phosphorus handling leading to vascular calcification in individuals with CKD., (Copyright © 2011 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Menopause is associated with urine phosphorus retention, which is mitigated by estrogen therapy. Fibroblast growth factor 23 (FGF-23) is a hormone originating from bone that regulates urine phosphorus excretion. Whether sex or estrogen therapy is associated with different FGF-23 levels is unknown., Study Design & Setting: Cross-sectional study of ambulatory individuals with prevalent cardiovascular disease., Predictors: Sex and, in women, use or nonuse of estrogen., Outcomes: Serum phosphorus, tubular maximum reabsorption of phosphorus indexed to glomerular filtration rate (TMP/GFR), and plasma FGF-23 concentrations., Results: For 987 participants, mean age was 67 ± 11 years, 182 (18%) were women, and 46 (25%) were using estrogen. Mean estimated GFR was 71 ± 23 (SD) mL/min/1.73 m(2). Compared with women who were not using estrogen, both women on estrogen therapy and men had significantly lower serum phosphorus concentrations, lower TMP/GFR values (indicating higher urine phosphorus excretion), and lower FGF-23 concentrations with adjustment for age, demographics, and kidney function (P < 0.001 for each). Mean FGF-23 levels were 68.7 (95% CI, 59.7-79.0) relative units (RU)/mL in non-estrogen-using women, 43.8 (95% CI, 41.2-46.5) RU/mL in men, and 45.1 (95% CI, 35.2-57.4) RU/mL in women using estrogen in adjusted analysis (P < 0.001)., Limitations: Most participants were men. Estrogen therapy was not randomly assigned., Conclusions: Older women who are not using estrogen have higher FGF-23 levels than either men or women using estrogen. In the context of prior literature, these data suggest that postmenopausal phosphorus retention may stimulate higher FGF-23 concentrations after menopause., (Published by Elsevier Inc.)

Background: The ACHIEVE (Optimizing the Treatment of Secondary Hyperparathyroidism: A Comparison of Sensipar and Low Dose Vitamin D vs Escalating Doses of Vitamin D Alone) trial evaluated the efficacy of treatment with cinacalcet plus low-dose activated vitamin D analogues (Cinacalcet-D) compared with vitamin D analogues alone (Flex-D) in attaining KDOQI (Kidney Disease Outcomes Quality Initiative) targets for secondary hyperparathyroidism (SHPT). The economic implications of these treatment regimens have not been explored., Study Design: Economic analysis of SHPT treatment in hemodialysis patients., Setting & Population: This analysis used data from the ACHIEVE trial, in which patients received either Cinacalcet-D or Flex-D., Model, Perspective, & Time Frame: We assessed the relative cost-effectiveness of these regimens in treating SHPT during the 27-week ACHIEVE trial, using a US payer perspective, with medication costs valued in 2006 US dollars. INTERVENTION & OUTCOMES: Relative cost-effectiveness was assessed using cost-minimization analysis or incremental cost-effectiveness ratios. Effectiveness was measured using biochemical markers., Results: Mean medication costs per patient were $5,852 and $4,332 for the Cinacalcet-D and Flex-D treatment arms, respectively. There were no significant differences for the primary end point (parathyroid hormone level of 150-300 pg/mL and calcium-phosphorus product < 55 mg²/dL²) and several of the secondary end points, rendering Cinacalcet-D more costly than Flex-D. For secondary end points, for which Cinacalcet-D was more effective, incremental cost-effectiveness ratios ranged from $2,957 (calcium < 9.5 mg/dL) to $22,028 (all KDOQI targets) per patient reaching target. Switching to generic calcitriol would have increased the cost difference between treatment arms ($2,079), whereas switching sevelamer to lanthanum decreased the difference ($1,426)., Limitations: Costs and outcomes were derived from a short-term randomized controlled trial and were protocol driven. Clinical outcomes, such as mortality, were not available. Long-term economic conclusions cannot be drawn from these data., Conclusions: Cinacalcet combined with vitamin D analogues was no more effective than vitamin D analogues in achieving the primary ACHIEVE end point and incurred greater costs. This conclusion was not tempered substantially by the cost of vitamin D analogues or oral phosphate binders. Whether the additional costs of cinacalcet are warranted will require longer term models to determine whether changes in serum levels of mineral metabolic markers translate into lower morbidity, mortality, and downstream costs., (Copyright © 2010 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Phosphorus binders are used to treat hyperphosphatemia in maintenance dialysis patients, in whom the use of these medications has been associated with lower mortality in some observational studies. It is not clear whether similar benefits can be seen in patients with non-dialysis-dependent chronic kidney disease (CKD)., Study Design: Historical cohort., Setting & Participants: 1,188 men with moderate and advanced non-dialysis-dependent CKD at a single medical center., Predictor: Administration of any phosphorus binder., Outcomes & Measurements: We examined associations of any phosphorus-binder administration with all-cause mortality and the slopes of estimated glomerular filtration rate using time-varying Cox models and mixed-effects models. Associations also were examined in intention-to-treat analyses and in 133 patient-pairs matched according to propensity scores., Results: 344 patients were treated with a phosphorus binder; 658 patients died (mortality rate, 141 deaths/1,000 patient-years; 95% CI, 131-153) during a median follow-up of 3.1 years. Treatment with phosphorus binders was associated with significantly lower mortality (adjusted HR, 0.61; 95% CI, 0.45-0.81; P < 0.001). Results were similar when exposure was modeled in intention-to-treat analyses and examining propensity-matched patients. Phosphorus-binder use was not associated with significant changes in kidney function loss., Limitations: Results may not apply to all patients with non-dialysis-dependent CKD., Conclusions: Administration of phosphorus binders is associated with lower mortality in men with moderate and advanced non-dialysis-dependent CKD. Clinical trials are needed to determine the risks and benefits of phosphorus-binder use in this patient population., (Published by Elsevier Inc.)

Background: Higher serum phosphorus levels are associated with cardiovascular disease (CVD) events in the general population, an association that may be stronger in men. Estradiol has phosphaturic properties. Whether higher serum phosphorus levels are associated with left ventricular (LV) mass in persons without end-stage renal disease and whether the association is modified by sex is unknown., Study Design: Cross-sectional observational study., Setting & Participants: 978 outpatients with stable CVD., Predictor: The primary predictor variable was serum phosphorus level. Sex was evaluated as an effect modifier., Outcome & Measurements: LV mass using transthoracic echocardiography., Results: The association of serum phosphorus level with LV mass differed by sex (interaction P=0.04). In models adjusted for age, race, kidney function, smoking, diabetes, blood pressure, cholesterol level, C-reactive protein level, and angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use, each 1-mg/dL higher serum phosphorus level was associated with 4.52-g/m2 greater LV mass (95% CI, 1.04-8.01; P=0.01) in men. Conversely, in women, no statistically significant association was found between serum phosphorus level and LV mass., Limitations: Older adult population with stable CVD; 19% were women., Conclusions: In outpatients with stable CVD, higher serum phosphorus levels are associated with greater LV mass in men, but not women. Whether sex hormones may account for these differences requires future study., (Copyright (c) 2010 National Kidney Foundation, Inc. All rights reserved.)

Background: Determination of parathyroid hormone (PTH) level is the most commonly used surrogate marker for bone turnover in patients with stage 5 chronic kidney disease on dialysis therapy (CKD-5D). The objective of this study is to evaluate the predictive value of various PTH measurements for identifying low or high bone turnover rate., Study Design: Diagnostic test study., Settings & Participants: 141 patients with CKD-5D from 15 US hemodialysis centers., Index Tests: Intact PTH, PTH 1-84, and PTH ratio (ratio of level of PTH 1-84 to level of large carboxy-terminal PTH fragments)., Reference Test or Outcome: Bone turnover determined using bone histomorphometry., Other Measurements: Demographic and treatment-related factors, serum calcium and phosphorus., Results: Patients presented histologically with a broad range of bone turnover abnormalities. In white patients with CKD-5D (n = 70), PTH ratio <1.0 added to intact PTH level <420 pg/mL increased the positive predictive value for low bone turnover from 74% to 90%. In black patients (n = 71), adding PTH ratio <1.2 to intact PTH level <340 pg/mL increased the positive predictive value for low bone turnover from 48% to 90%. Adding PTH ratio >1.6 to intact PTH level of 340-790 pg/mL increased the positive predictive value for high bone turnover from 56% to 71%., Limitations: Because the research protocol called for carefully controlled blood specimen handling, blood drawing and routine specimen handling might be less stringent in clinical practice. By limiting study participation to black and white patients with CKD-5D, we cannot comment on the roles of intact PTH, PTH 1-84, and PTH ratio in other racial/ethnic groups., Conclusion: In black patients with CKD-5D, the addition of PTH ratio to intact PTH measurements is helpful for diagnosing low and high bone turnover. In white patients with CKD-5D, it aids in the diagnosis of low bone turnover., (Copyright 2010 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Incremental achievement of quality indicator goals has been associated with progressive improvement in mortality and hospitalization risk in hemodialysis (HD) patients., Study Design: Descriptive cross-sectional study., Setting & Participants: All 33,879 HD patients treated at Fresenius Medical Care North America facilities for >90 days with scorable 36-Item Short Form Health Survey responses from January 1, 2006, to December 31, 2006., Predictor: We hypothesized that achieving up to 5 HD goals before the survey (albumin >or= 4.0 g/dL, hemoglobin of 11-12 g/dL, equilibrated Kt/V >or= 1.2, phosphorus of 3.5-5.5 mg/L, and absence of HD catheter) results in better self-reported quality of life (QoL)., Outcomes & Measurements: Distributions of Physical and Mental Component Summary (PCS/MCS) scores within and across quality indicator categories determined during the prior 90 days from survey date (compared using analysis of covariance and linear regression models, with adjustment for case-mix and each of the quality indicators)., Results: Incremental achievement of up to 5 goals was associated with progressively higher PCS and MCS scores (both P for trend < 0.001). Compared with patients meeting all 5 goals (n = 4,208; reference group), case-mix-adjusted PCS score was lower by 1.8 point with only 4 goals met (n = 11,785), 3.4 points for 3 goals (n = 10,906), 4.9 points for 2 goals (n = 5,119), 5.9 points for 1 goal (n = 1,592), and 7.8 points in the 269 patients who failed to meet any goal (each P < 0.001 vs the reference group). The corresponding decreases in case-mix-adjusted MCS scores were 1.0 point for 4 goals met, 1.7 point for 3 goals, 2.3 points for 2 goals, 3.0 points for 1 goal, and 4.7 points with no goal met, with each P < 0.001 compared with the MCS score from patients who achieved all 5 goals., Limitations: Potential residual confounding from unmeasured covariates., Conclusion: Patients progressively meeting more quality goals report incrementally better QoL. Further studies are needed to determine whether prospective achievement of quality goals will result in improved QoL for HD patients.

Background: Vitamin D has key roles in regulating systems that could be important in the pathobiological state of proteinuria. Because of this, it could be helpful in treating patients with proteinuric renal diseases. The objective is to determine the effect of oral paricalcitol on protein excretion in patients with proteinuric chronic kidney disease., Study Design: Double-blind randomized study., Setting & Participants: 61 patients with estimated glomerular filtration rate of 15 to 90 mL/min/1.73 m(2) and protein excretion greater than 400 mg/24 h., Intervention: Randomization to 6 months of treatment with paricalcitol, 1 mug/d, or placebo., Outcomes & Measurements: The predefined primary end point was to compare change in mean spot urinary protein-creatinine ratio between the baseline measurement and the last study evaluation (6 months in study completers) between the 2 groups. Every 4 weeks, there was measurement of serum intact parathyroid hormone, serum calcium, serum phosphorus, serum creatinine, and urine spot protein and creatinine., Results: At baseline, mean urinary protein-creatinine ratios were 2.6 and 2.8 g/g in the placebo and paricalcitol groups, respectively. At final evaluation, mean ratios were 2.7 and 2.3, respectively. Changes in protein excretion from baseline to last evaluation were +2.9% for controls and -17.6% for the paricalcitol group (P = 0.04). A 10% decrease in proteinuria occurred in controls (7 of 27; 25.9%) and the paricalcitol group (16 of 28; 57.1%; P = 0.03)., Limitations: The relatively small sample size limits the extent to which results should be generalized., Conclusions: Paricalcitol resulted in a significant reduction in protein excretion in patients with proteinuric renal disease.

Background: Phosphate binders are widely used to control serum phosphorus levels in patients with chronic kidney disease (CKD). We analyzed the effects of phosphate binders on biochemical and patient-level end points in patients with CKD., Study Design: Systematic review and meta-analysis by searching MEDLINE (1966 to April 2009), EMBASE (1980 to April 2009), and the Cochrane Renal Group Specialised Register and the Cochrane Central Register of Controlled Trials (CENTRAL)., Setting & Population: Patients with CKD., Selection Criteria for Studies: Randomized controlled trials., Intervention: Phosphate binders., Outcomes: Serum phosphorus, calcium, and parathyroid hormone levels; incidence of hypercalcemia; all-cause mortality; adverse effects., Results: 40 trials (6,406 patients) were included. There was no significant decrease in all-cause mortality (10 randomized controlled trials; 3,079 patients; relative risk [RR], 0.73; 95% confidence interval [CI], 0.46 to 1.16), hospitalization, or end-of-treatment serum calcium-phosphorus product levels with sevelamer compared with calcium-based agents. There was a significant decrease in end-of-treatment phosphorus and parathyroid hormone levels with calcium salts compared with sevelamer and a significant decrease in risk of hypercalcemia (RR, 0.47; 95% CI, 0.36 to 0.62) with sevelamer compared with calcium-based agents. There was a significant increase in risk of gastrointestinal adverse events with sevelamer in comparison to calcium salts (RR, 1.39; 95% CI, 1.04 to 1.87). Compared with calcium-based agents, lanthanum significantly decreased end-of-treatment serum calcium and calcium-phosphorus product levels, but with similar end-of-treatment phosphorus levels. Effects of calcium acetate on biochemical end points were similar to those of calcium carbonate. Existing data are insufficient to conclude for a differential impact of any phosphate binder on cardiovascular mortality or other patient-level outcome., Limitations: Few long-term studies of the efficacy of phosphate binders on mortality and musculoskeletal morbidity, significant heterogeneity for many surrogate outcomes, and suboptimal reporting of study methods to determine trial quality., Conclusion: Currently, there are insufficient data to establish the comparative superiority of non-calcium-binding agents over calcium-containing phosphate binders for such important patient-level outcomes as all-cause mortality and cardiovascular end points. Additional trials are still required to examine the differential effects of phosphate-binding agents on these end points and the mineral homeostasis pathway.

Background: Cardiovascular disease (CVD) is the most common cause of death in patients with chronic kidney disease (CKD). Secondary hyperparathyroidism is common in patients with CKD, and its relationship to CVD is not well defined. This analysis aims to assess whether serum intact parathyroid hormone (PTH) level is an independent risk factor for CVD in patients with CKD stages 3 and 4., Methods: In this cross-sectional study, medical history surveys, including CVD events, were collected from 4,472 patients with stages 3 and 4 CKD identified by the National Kidney Foundation Kidney Early Evaluation Program (KEEP), which included blood pressure measurement and laboratory testing. Age, hemoglobin level, estimated glomerular filtration rate, serum phosphorus level, and serum calcium level were evaluated as continuous variables, and plasma PTH levels, by tertile: less than 35, 35 to 70, and greater than 70 pg/mL. Multivariate logistic regression was used to estimate odds ratios (ORs) of CVD predictor variables., Results: Mean age was 68.3 +/- 11.8 years. Of the study population, 68% were women, 69% were white, 6% were current smokers, 45% were obese, 46% had diabetes, and 83% had hypertension. A history of CVD was present for 1,972 (44.1%), and plasma PTH level greater than 70 pg/mL, for 2,239 (50.1%). Multivariate logistic regression showed ORs for CVD events increasing with age (OR, 1.03; P < 0.001), male sex (OR, 1.51; P < 0.001), diabetes (OR, 1.73; P < 0.001), hypertension (OR, 1.43; P < 0.001), and intact PTH level greater than 70 pg/mL (OR, 1.51; P < 0.001; reference, <35 pg/mL)., Conclusions: PTH level greater than 70 pg/mL is independently associated with CVD events in patients with CKD stages 3 and 4. No association was observed between serum phosphorus or calcium level and CVD events. These findings provide support for intact PTH testing, along with testing for other indicators of CKD mineral and bone disorders, at earlier CKD stages.

Background: Higher serum phosphorus concentrations within the normal laboratory range have been associated with cardiovascular events and mortality in large prospective cohort studies of individuals with and without kidney disease. Reasons for interindividual variation in steady-state serum phosphorus concentrations are largely unknown., Study Design: Cross-sectional study., Setting & Participants: 15,513 participants in the Third National Health and Nutrition Examination Survey., Predictors: Demographic data, dietary intake measured by means of 24-hour dietary recall and food-frequency questionnaire, and established cardiovascular risk factors., Outcome & Measurements: Serum phosphorus concentration., Results: Mean serum phosphorus concentrations were significantly greater in women (+0.16 mg/dL versus men; P < 0.001) and people of non-Hispanic black and Hispanic race/ethnicity (+0.06 and +0.07 mg/dL versus non-Hispanic white, respectively; P < 0.001). Dietary intakes of phosphorus and phosphorus-rich foods were associated only weakly with circulating serum phosphorus concentrations, if at all. Higher serum phosphorus levels were associated with lower calculated Framingham coronary heart disease risk scores, which are based on traditional atherosclerosis risk factors. In aggregate, demographic, nutritional, cardiovascular, and kidney function variables explained only 12% of the variation in circulating serum phosphorus concentrations., Limitations: Results may differ with advanced kidney disease., Conclusions: Serum phosphorus concentration is weakly related to dietary phosphorus and not related to a diverse array of phosphorus-rich foods in the general population. Factors determining serum phosphorus concentration are largely unknown. Previously observed associations of serum phosphorus concentrations with cardiovascular events are unlikely to be a result of differences in dietary intake or traditional cardiovascular risk factors.

Background: Secondary hyperparathyroidism is observed in patients with early chronic kidney disease (CKD). This study investigated the safety and efficacy of cinacalcet for secondary hyperparathyroidism in participants with CKD not receiving dialysis., Study Design: Double-blind, randomized, 32-week, phase 3 study., Setting & Participants: 404 participants with stage 3 or 4 CKD from 73 centers in 9 countries., Interventions: Cinacalcet:placebo (3:1 ratio)., Outcomes & Measurements: Proportion of participants with a mean decrease of 30% or greater in intact parathyroid hormone (iPTH) level, proportion with iPTH level of 70 or less or 110 or less pg/mL (stage 3 and 4 CKD, respectively), and mean percentage of iPTH change from baseline, all during the efficacy-assessment phase., Results: A greater proportion of cinacalcet than placebo participants achieved a 30% or greater decrease in iPTH level (74% versus 28%; P < 0.001), corresponding to a 43.1% decrease in iPTH level from baseline (cinacalcet) compared with a 1.1% increase (placebo). At week 32, serum calcium levels were 8.9 +/- 0.8 mg/dL (-8.9%; cinacalcet) and 9.9 +/- 0.6 mg/dL (+0.8%; placebo), phosphorus levels were 4.5 +/- 1.0 mg/dL (+21.4%) and 4.0 +/- 0.7 mg/dL (+6.8%), and calcium-phosphorus product values were 40.1 +/- 8.3 mg(2)/dL(2) (+18.9%) and 38.9 +/- 6.9 mg(2)/dL(2) (+17.1%), respectively. During the study course, 62% (cinacalcet) and 1% (placebo) of participants experienced 2 consecutive serum calcium concentrations less than 8.4 mg/dL. They generally were asymptomatic and without significant clinical consequences. Treatment generally was well tolerated, and most adverse events were mild to moderate in severity., Limitations: The study was not designed to assess the effects of cinacalcet on vascular calcification, bone histomorphometric parameters, or other clinical outcomes. It is not known whether the observed differences in changes in iPTH levels are clinically more important than observed differences in changes in serum calcium or phosphorus levels or dosages of vitamin D sterols and phosphate binders., Conclusions: These data show that cinacalcet treatment in patients with CKD not receiving dialysis can decrease plasma iPTH levels, but with frequent (albeit generally asymptomatic) serum calcium levels less than 8.4 mg/dL and increases in serum phosphorus levels.

Background: To determine the most significant potentially actionable clinical variables associated with mortality and hospitalization risk in hemodialysis (HD) patients., Study Design: Cohort study., Setting & Participants: Adult maintenance HD patients in the Fresenius Medical Care, North America database as of January 1, 2004, with baseline information from October 1, 2003, to December 31, 2003, comprising approximately 26% of the US HD population., Predictors: Case-mix (age, sex, race, diabetes, vintage, and body surface area), vascular access, and laboratory (albumin, equilibrated Kt/V, hemoglobin, calcium, phosphorus, creatinine, bicarbonate, biointact parathyroid hormone, transferrin saturation, and white blood cell count) variables., Outcomes: 1-year mortality and hospitalization risk from January 1 to December 31, 2004., Measurements: Cox proportional hazards models for death and hospitalization., Results: The cohort (N = 78,420) had a mean age of 61.4 +/- 15.0 years, 47% were women, 49% were white, 41% were black race (10% defined as "other"), and 52% had diabetes. The top 5 actionable variables were the same for mortality and hospitalization. Final case-mix plus laboratory-adjusted hazard ratios for these top 5 actionable variables indicate 177% increased risk of death and 67% increased risk of hospitalization per 1-g/dL decrease in albumin level, 39% and 45% greater risk with catheters compared with fistulas, 18% and 9% greater risk per 1-mg/dL greater phosphorus level, 11% and 9% lower risk per 1-g/dL greater hemoglobin level, and 5% and 2% greater risk per 0.1-unit decrease in equilibrated Kt/V, respectively (all P < 0.0001)., Limitations: Observational cross-sectional study with limited comorbidity adjustment (for diabetes)., Conclusion: The same variables are associated with both mortality and hospitalization in HD patients. The top 5 potentially actionable variables are readily identifiable, with albumin level and catheter use the most prominent, and all 5 are appropriate targets for improvement.

Background: In kidney transplant recipients, persistent hyperparathyroidism leads to hypercalcemia and increased urinary phosphorus excretion. The calcimimetic drug cinacalcet effectively decreases parathyroid hormone (PTH) levels and corrects hypercalcemia in these patients. The purpose of the present study is to examine the effect of cinacalcet treatment on determinants of renal phosphorus reabsorption under steady-state conditions., Study Design: Open-label prospective uncontrolled trial., Setting & Participants: 10 stable kidney transplant recipients with persistent hyperparathyroidism., Intervention: Cinacalcet, 30 and 60 mg/d, for 2 weeks., Outcomes & Measures: Changes in urinary phosphorus excretion in timed urine samples, intact and carboxy-terminal (C-term) fibroblast growth factor 23 (FGF-23), intact PTH, venous pH, and bicarbonate values at defined intervals over 24 hours., Results: Cinacalcet decreased renal phosphorus excretion in the first 8 hours by 30% to 40%, but not from 8 to 24 hours after drug administration. Serum phosphorus levels normalized in all patients. Cinacalcet markedly decreased plasma intact PTH levels (60%; P < 0.001). Cinacalcet also decreased mean intact FGF-23 levels from 67 +/- 8 (SE) to 51 +/- 5 and to 54 +/- 6 pg/mL (P < 0.001) and mean C-term FGF-23 levels from 108 +/- 15 to 87 +/- 9 and to 101 +/- 9 RU/mL (P < 0.01), respectively. There was high correlation between intact FGF-23 and C-term FGF-23 levels (r = 0.598; P < 0.001). Acid-base status was unchanged., Limitations: This is a small study and does not examine the long-term effect of cinacalcet treatment., Conclusions: Cinacalcet effectively corrected urinary phosphate wasting in kidney transplant recipients, resulting in normalization of serum phosphorus levels. The phosphatemic effects of cinacalcet correlated with a marked decrease in the phosphaturic hormone PTH, rather than with a change in FGF-23 levels or acid-base status, highlighting the importance of PTH in posttransplantation hypophosphatemia.

Background: Abnormalities in serum calcium, phosphorus, and parathyroid hormone (PTH) concentrations are common in patients with chronic kidney disease and have been associated with increased morbidity and mortality. No clinical trials have been conducted to clearly identify categories of calcium, phosphorus, and PTH levels associated with the lowest mortality risk. Current clinical practice guidelines are based largely on expert opinions, and clinically relevant differences exist among guidelines across countries. We sought to describe international trends in calcium, phosphorus, and PTH levels during 10 years and identify mortality risk categories in the Dialysis Outcomes and Practice Patterns Study (DOPPS), an international study of hemodialysis practices and associated outcomes., Study Design: Prospective cohort study., Participants: 25,588 patients with end-stage renal disease on hemodialysis therapy for longer than 180 days at 925 facilities in DOPPS I (1996-2001), DOPPS II (2002-2004), or DOPPS III (2005-2007)., Predictors: Serum calcium, albumin-corrected calcium (Ca(Alb)), phosphorus, and PTH levels., Outcomes: Adjusted hazard ratios for all-cause and cardiovascular mortality calculated using Cox models., Results: Distributions of mineral metabolism markers differed across DOPPS countries and phases, with lower calcium and phosphorus levels observed in the most recent phase of DOPPS. Survival models identified categories with the lowest mortality risk for calcium (8.6 to 10.0 mg/dL), Ca(Alb) (7.6 to 9.5 mg/dL), phosphorus (3.6 to 5.0 mg/dL), and PTH (101 to 300 pg/mL). The greatest risk of mortality was found for calcium or Ca(Alb) levels greater than 10.0 mg/dL, phosphorus levels greater than 7.0 mg/dL, and PTH levels greater than 600 pg/mL and in patients with combinations of high-risk categories of calcium, phosphorus, and PTH., Limitations: Because of the observational nature of DOPPS, this study can only indicate an association between mineral metabolism categories and mortality., Conclusions: Our results provide important information about mineral metabolism trends in hemodialysis patients in 12 countries during a decade. The risk categories identified in the DOPPS cohort may be relevant to efforts at international harmonization of existing clinical guidelines for mineral metabolism.

Background: Secondary hyperparathyroidism is a common complication in children receiving hemodialysis. Active vitamin D is an effective therapy, but its use is often limited by hypercalcemia and increased calcium x phosphorus (Ca x P) product. Paricalcitol, a selective vitamin D receptor activator, causes less sustained hypercalcemia and increase in Ca x P product than calcitriol and has been used effectively in adult hemodialysis patients., Study Design: Double blind, placebo-controlled., Setting & Participants: Hemodialysis units and pediatric subjects receiving hemodialysis., Intervention: After a washout period of 2 to 6 weeks, 29 subjects aged 5 to 19 years received either paricalcitol or placebo for up to 12 weeks (0.04 mug/kg if initial intact parathyroid hormone [iPTH] level < 500 pg/mL [ng/L]; 0.08 mug/kg if initial iPTH level > 500 pg/mL [ng/L]). The dose was increased by 0.04 mug/kg every 2 weeks until there was a 30% decrease in iPTH level from baseline or calcium level greater than 11 mg/dL (>2.74 mmol/L) or Ca x P product greater than 75 mg(2)/dL(2) (>6.04 mmol(2)/L(2))., Outcomes & Measurements: Two consecutive 30% decreases from baseline in iPTH levels and safety of paricalcitol, including hypercalcemia and increase in Ca x P product., Results: 60% of the paricalcitol group had 2 consecutive 30% decreases from baseline iPTH levels compared with 21% in the placebo group (P = 0.06). The paricalcitol group had a mean decrease in iPTH level of 164 pg/mL (ng/L), whereas the placebo group had a mean increase of 238 pg/mL (ng/L; P = 0.03). There was no difference from baseline to final visit in calcium, phosphorus, or Ca x P product values in either group., Limitations: Low power to detect differences in safety between groups and a short-term study., Conclusion: Paricalcitol decreased iPTH levels in children receiving hemodialysis with no significant changes in serum calcium, phosphorus, or Ca x P product values during the course of the study.

Background: Patients with renal failure require complex regimens of renal replacement therapies and medications, including ingestion of phosphate-binding agents 3 times daily. Previous studies suggested that sevelamer may provide extended phosphate binding and be effective with once-daily dosing, thus simplifying the phosphate-binder regimen., Methods: Twenty-four patients were enrolled in this study, 21 of whom were randomly assigned to sevelamer administration at their previously prescribed dose, either once daily with the largest meal or thrice daily with meals, with crossover to the other regimen after 4 weeks. Eighteen patients completed both treatment periods. The primary efficacy measure for which the study was powered is comparison of the effect of once-daily versus standard thrice-daily sevelamer dosing on serum phosphorus level control, determined by using equivalence testing. Secondary efficacy measures are the effects of the 2 regimens on serum calcium level corrected for albumin level; calcium x phosphorus product; albumin; intact parathyroid hormone; total, low-density lipoprotein, high-density lipoprotein, and non-high-density lipoprotein cholesterol; and triglyceride levels., Results: Once-daily sevelamer was as effective as thrice-daily dosing of sevelamer in controlling serum phosphorus, calcium, calcium x phosphorus product, serum albumin, and serum lipid levels. Bioequivalence was not shown for intact parathyroid hormone, likely because of high variability. Mean serum phosphorus levels were 4.6 +/- 0.3 mg/dL (1.49 +/- 0.10 mmol/L) during thrice-daily dosing and 5.0 +/- 0.3 mg/dL (1.61 +/- 0.10 mmol/L) during once-daily dosing. The average prescribed dose of sevelamer during both treatment regimens was 6.7 +/- 2.4 g. Routine laboratory measures were similar in the 2 groups. Both regimens were well-tolerated., Conclusion: Despite concerted patient-directed educational efforts, phosphorus level control in patients with renal failure is suboptimal and contributes to increased mortality risk. Once-daily sevelamer could simplify these regimens and encourage medication compliance, perhaps improving hyperphosphatemia management.

Background: Few investigations have described fracture risk and its relation to disorders in calcium (Ca), phosphorus (P), and parathyroid hormone (PTH) metabolism in the end-stage renal disease population., Methods: Laboratory values for Ca, P, and PTH were obtained from Dialysis Morbidity and Mortality Study (DMMS) Waves 1 to 4. Additional data available from the US Renal Data System were used to determine the incidence and associated costs of hip, vertebral, and pelvic fractures in 9,007 patients with nonmissing laboratory values and Medicare as primary payor. Cox proportional hazards and Poisson models were used to analyze time to first fracture and numbers of fractures, respectively., Results: There was no association between Ca or P values and risk for fracture; risks for vertebral and hip fractures and PTH concentrations were U shaped and weakly significant using Poisson regression (P = 0.03). The age- and sex-adjusted mortality rate after fracture was 2.7 times greater (580/1,000 person-years) than for general dialysis patients from the DMMS (217/1,000 person-years). Mean total episodic costs of hip, vertebral, and pelvic fractures were 20,810 dollars +/- 16,743 dollars (SD), 17,063 dollars +/- 26,201 dollars, and 14,475 dollars +/- 19,209 dollars, respectively., Conclusion: Using data from the DMMS, there were no associations between Ca and P concentrations and risk for fracture. Risks for hip and vertebral fracture were associated weakly with PTH concentration, with the lowest risk observed around a PTH concentration of 300 pg/mL (ng/L). Fractures were associated with high subsequent mortality and costs. Prospective studies are needed to determine whether therapies that maintain PTH concentrations within or near the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative range will result in fewer complications of disordered mineral metabolism.

Background: Children with end-stage renal disease (ESRD) receiving hemodialysis may have their care overseen primarily by a pediatric nephrologist or internal medicine (IM) nephrologist., Methods: To examine specific clinical outcomes by nephrologist specialization, a cross-sectional analysis of demographic and clinical data collected in the 2002 ESRD Clinical Performance Measures Project was performed., Results: Of 653 pediatric patients meeting inclusion criteria, 27% were cared for by IM nephrologists, and 73%, by pediatric nephrologists. Pediatric nephrologists were significantly more likely than IM nephrologists to care for patients who were younger and of Hispanic ethnicity. Patients of pediatric compared with IM nephrologists also were more likely to have a congenital cause of ESRD, smaller body mass index, and longer time on dialysis therapy. No significant differences in achieving a mean Kt/V of 1.2 or greater or mean hemoglobin level of 11 g/dL or greater (> or =110 g/L) according to nephrologist specialization were observed. After adjustment for patient clinical characteristics, no significant difference in use of arteriovenous fistulae was observed. Patients cared for by pediatric nephrologists were less likely to achieve a mean serum albumin level of 4.0/3.7 g/dL (40/37 g/L; bromcresol green laboratory method/bromcresol purple laboratory method; adjusted odds ratio, 0.60; 95% confidence interval, 0.42 to 0.86). Patients cared for by pediatric nephrologists had significantly greater serum calcium levels, lower serum phosphate levels, and lower intact parathyroid hormone levels., Conclusion: Using adult-focused clinical care targets, care provided by pediatric and IM nephrologists to pediatric patients receiving hemodialysis in the United States is similar. However, differences exist, and the significance of these differences requires further study.

Background: In 2003, the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative (K/DOQI) published a guideline recommending tight control of serum calcium, phosphorus, calcium-phosphorus product (Ca x P), and intact parathyroid hormone levels in patients with chronic kidney disease. Within the context of this guideline, we explored associations of these plasma concentrations with all-cause mortality risk in incident dialysis patients in The Netherlands., Methods: In a large, prospective, multicenter, cohort study (Netherlands Cooperative Study on the Adequacy of Dialysis), we included 1,629 patients new on hemodialysis or peritoneal dialysis therapy between 1997 and 2004. Multivariate Cox regression models containing calcium level, phosphorus level, intact parathyroid hormone level, age, comorbidity, primary kidney disease, nutritional status, albumin level, dialysis dose, and hemoglobin level were used to examine mortality risks., Results: Mean age was 60 +/- 15 (SD) years, 61% were men, and 64% were treated with hemodialysis. In adjusted time-dependent survival analysis, all-cause mortality risk increased in hemodialysis patients by 40% (hazard ratio [HR], 1.4; 95% confidence interval [CI], 1.1 to 1.7) and in peritoneal dialysis patients by 60% (HR, 1.6; 95% CI, 1.1 to 2.4) for plasma phosphorus levels greater than the target. In addition, having elevated plasma Ca x P product levels increased mortality risk by 40% (HR, 1.4; 95% CI, 1.1 to 1.8) in hemodialysis patients and 50% in peritoneal dialysis patients (HR, 1.5; 95% CI, 1.0 to 2.2). In both patient groups, no significant effects were observed for plasma levels less than the targets., Conclusion: In time-dependent survival analysis, the presence of plasma phosphorus and Ca x P product concentrations greater than K/DOQI targets increased all-cause mortality risk in hemodialysis and peritoneal dialysis patients.

Background: In 1991, the World Health Organization (WHO) initiated a cross-cultural project to develop a quality-of-life (QOL) questionnaire (WHOQOL); soon after this, the clinically applicable short form was developed and named WHOQOL-BREF, followed by a Taiwanese version (WHOQOL-BREF[TW])., Methods: We first administered the WHOQOL-BREF(TW) and symptom/problem scale to 376 patients with end-stage renal disease on regular hemodialysis therapy in Taiwan. Analysis with multiple stepwise regressions was conducted to study determinants of QOL domains and items., Results: The WHOQOL-BREF(TW) was reliable and valid from various validation studies. The 4 domains (physical, psychological, social relations, and environment) and global items (overall quality of life and general health) of the WHOQOL-BREF(TW) each differentiated symptoms/problems of hemodialysis patients from age-, sex-, and education-matched healthy referents. The 4 domains, except for environment and global items of the WHOQOL-BREF(TW), each differentiated erythropoietin dosage from age-, sex-, and education-matched healthy referents. After adjusting for age, sex, marriage, and education, the prominent associated factors of various QOL domains and items were age, area (Taipei or Keelung), hemoglobin level, normalized protein catabolic rate, and symptom/problem scale., Conclusion: The WHOQOL-BREF(TW) is reliable and valid for long-term study of hemodialysis patients, and hemodialysis had negative impacts on QOL, especially in patients with more severe disease with greater symptom/problem scores, lower hemoglobin levels, and lower normalized protein catabolic rates.

Background: Abnormalities of mineral metabolism are prevalent in patients with kidney failure and are associated with increased risk for cardiovascular events. There are limited data investigating relationships of phosphorus and calcium-phosphorus product with outcomes in patients with chronic kidney disease (CKD) stages 3 to 4., Methods: Serum phosphorus and calcium were measured at baseline in 840 participants from the randomized cohort of the Modification of Diet in Renal Disease Study. Survival status until December 31, 2000, was obtained from the National Death Index. Cox models were performed to assess the relationship of serum phosphorus level and calcium-phosphorus product with all-cause and cardiovascular disease (CVD) mortality., Results: Mean serum phosphorus level was 3.8 +/- 0.7 mg/dL (1.23 +/- 0.23 mmol/L), calcium-phosphorus product was 34.7 +/- 6.3 mg2/dL2, and glomerular filtration rate (GFR) was 33 +/- 12 mL/min/1.73 m2 (0.55 +/- 0.20 mL/s/1.73 m2). All-cause and CVD mortality rates were 25% and 15%. Serum phosphorus level was not related to all-cause mortality in multivariable models (P = 0.46). In unadjusted analysis, serum phosphorus level was associated with (hazard ratio [HR] per 1 mg/dL increase, 1.34; 95% confidence interval [CI], 1.05 to 1.71; P = 0.02) increased risk for CVD mortality, but this association was partly attenuated and not statistically significant after adjustment for GFR and other confounders (HR, 1.27; 95% CI, 0.94 to 1.73; P = 0.12). Calcium-phosphorus product was not associated with all-cause mortality in unadjusted (P = 0.23) or multivariate analysis (P = 0.35). Calcium-phosphorus product was related to CVD mortality in unadjusted (HR per 10 mg2/dL2 increase, 1.30; 95% CI, 1.01 to 1.69; P = 0.04) analysis, but this association was not statistically significant after adjustment for GFR and other confounders (HR, 1.22; 95% CI, 0.89 to 1.66; P = 0.23)., Conclusion: In the Modification of Diet in Renal Disease Study cohort, serum phosphorus level and calcium-phosphorus product were not statistically associated with all-cause or CVD mortality after adjustment for GFR; however larger studies with additional statistical power are needed to evaluate these relationships, especially in the context of current practice patterns in patients with CKD.

Background: Secondary hyperparathyroidism develops early in patients with chronic kidney disease (CKD). Clinical guidelines from the National Kidney Foundation-Kidney/Disease Outcomes Quality Initiative emphasize the need to control parathyroid hormone (PTH), calcium, and phosphorus levels in patients with CKD not receiving dialysis to reduce poor outcomes. This phase 2 study evaluated the effects of the oral calcimimetic cinacalcet hydrochloride in patients with CKD not on dialysis therapy., Methods: A randomized, double-blind, placebo-controlled, 18-week study enrolled adults with an estimated glomerular filtration rate of 15 to 50 mL/min/1.73 m2 (0.25 to 0.83 mL/s/1.73 m2) and an intact PTH (iPTH) level greater than 130 pg/mL (ng/L). Cinacalcet (or placebo) was titrated from 30 to 180 mg once daily to obtain a 30% or greater reduction in iPTH levels from baseline., Results: Baseline mean iPTH levels were 243 pg/mL (ng/L) in the cinacalcet group (n = 27) and 236 pg/mL (ng/L) in the control group (n = 27). At baseline, 28% of subjects were being administered vitamin D sterols and 43% were being administered phosphate binders or calcium supplements. The addition of cinacalcet significantly decreased iPTH concentrations compared with controls during the efficacy-assessment phase: 56% versus 19% of subjects achieved a 30% or greater reduction in iPTH levels (P = 0.006), and mean iPTH levels decreased by 32% in the cinacalcet group, but increased by 6% in the control group (P < 0.001). Mean serum calcium and phosphorus levels remained within normal range throughout the study. Cinacalcet generally was well tolerated; the most frequent adverse events were gastrointestinal., Conclusion: This preliminary study provides evidence that cinacalcet is efficacious for the treatment of secondary hyperparathyroidism in subjects with CKD not receiving dialysis.

Background: Recent Kidney Disease Outcomes Quality Initiative guidelines have raised concerns of 25-hydroxyvitamin D, or calcidiol, insufficiency and deficiency in patients with chronic kidney disease (CKD) not yet on dialysis therapy; however, no cross-sectional study across latitudes has been performed to support this assertion., Methods: Baseline screening data from a prospective study were used to determine calcidiol levels in subjects with moderate to severe CKD not yet on dialysis therapy from 12 geographically diverse regions of the United States. Calcidiol deficiency is defined as levels less than 10 ng/mL (< 25 nmol/L), and insufficiency, as levels of 10 to 30 ng/mL (25 to 75 nmol/L)., Results: Two hundred one subjects with a mean age 65 +/- 13 years and calculated glomerular filtration rate (GFR) of 27 +/- 11 mL/min (0.45 mL/s) were evaluated. Overall mean calcidiol level was 19.4 +/- 13.6 ng/mL (48 +/- 34 nmol/L), with a range of 0 to 65 ng/mL (0 to 162 nmol/L). Only 29% and 17% of subjects with moderate and severe CKD had sufficient levels, respectively. Mean calcidiol levels were less than sufficient levels in all geographic locations tested. Multivariate analysis found log calcidiol level correlated with calcium level (P = 0.016), log calcitriol level (P = 0.024), sex (P = 0.041), geographic location (P = 0.045), and inverse intact parathyroid hormone level (P = 0.013), but not calculated GFR or phosphorous level. Calcidiol levels changed modestly in 18 patients who had calcidiol levels measured in winter and late summer after confirmed exposure to sunlight, with mean calcidiol levels of 17.9 +/- 11.7 to 21.2 +/- 10.0 ng/mL (45 +/- 29 to 53 +/- 25 nmol/L; P = 0.015)., Conclusion: This cross-sectional cohort study found a high prevalence of calcidiol deficiency and insufficiency in patients with moderate and severe CKD not on dialysis therapy regardless of geographic location.