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Purpose: Vitamin C deficiency is associated with excess mortality in kidney transplant recipients (KTR). We aim to evaluate plasma vitamin C status at different post-transplantation moments and assess the main characteristics associated with vitamin C deficiency in KTR. Methods: Plasma vitamin C was assessed in 598 KTR at 3-, 6-, 12-, 24-, and 60-months post-transplantation, 374 late KTR with a functioning graft ≥ 1 year, and 395 potential donors. Vitamin C deficiency was defined as plasma vitamin C ≤ 28 µmol/L. Diet was assessed by a 177-item food frequency questionnaire. Data on vitamin C-containing supplements use were extracted from patient records and verified with the patients. Results: Vitamin C deficiency ranged from 46% (6-months post-transplantation) to 30% (≥ 1 year post-transplantation). At all time points, KTR had lower plasma vitamin C than potential donors (30–41 µmol/L vs 58 µmol/L). In cross-sectional analyses of the 953 KTR at their first visit ≥ 12 months after transplantation (55 ± 14 years, 62% male, eGFR 55 ± 19 mL/min/1.73 m2), the characteristics with the strongest association with vitamin C deficiency were diabetes and smoking (OR 2.67 [95% CI 1.84–3.87] and OR 1.84 [95% CI 1.16–2.91], respectively). Dietary vitamin C intake and vitamin C supplementation were associated with lower odds (OR per 100 mg/day 0.38, 95% CI 0.24–0.61 and OR 0.21, 95% CI 0.09–0.44, respectively). Conclusion: Vitamin C deficiency is frequent among KTR regardless of the time after transplantation, especially among those with diabetes and active smokers. The prevalence of vitamin C deficiency was lower among KTR with higher vitamin C intake, both dietary and supplemented. Further research is warranted to assess whether correcting this modifiable risk factor could improve survival in KTR. [ABSTRACT FROM AUTHOR]

This article discusses the potential use of plasma symmetric dimethylarginine (SDMA) as a marker of kidney function in kidney transplant recipients (KTRs). The current measures of kidney function, such as creatinine and estimated glomerular filtration rate (eGFR), have limitations, particularly in patients with low muscle mass. SDMA, which is produced in almost all nucleated cells and solely cleared by the kidneys, may provide a muscle mass-independent marker of kidney function. The study found that plasma SDMA correlated more strongly with measured GFR than creatinine in two large cohorts of KTRs. Additionally, higher SDMA levels were associated with a higher risk of graft failure, independent of other factors. The findings suggest that SDMA may be a valuable marker of kidney function, especially in patients with low muscle mass. However, further research is needed to validate these findings in diverse populations and compare SDMA with other kidney function markers. [Extracted from the article]

Optimization of individual immunosuppression, which reduces the risks of both graft loss and patients' death, is considered the best approach to improve long‐term outcomes of renal transplantation. Torque Teno Virus (TTV) DNAemia has emerged as a potential biomarker reflecting the depth of therapeutic immunosuppression during the initial year post‐transplantation. However, its efficacy in long‐term monitoring remains uncertain. In a cohort study involving 34 stable kidney transplant recipients and 124 healthy volunteers, we established lower and upper TTV DNAemia thresholds (3.75–5.1 log10 cp/mL) correlating with T‐cell activatability, antibody response against flu vaccine, and risk for subsequent serious infections or cancer over 50 months. Validation in an independent cohort of 92 recipients confirmed that maintaining TTV DNAemia within this range in >50% of follow‐up time points was associated with reduced risks of complications due to inadequate immunosuppression, including de novo DSA, biopsy‐proven antibody‐mediated rejection, graft loss, infections, or cancer. Multivariate analysis highlighted "in‐target" TTV DNAemia as the sole independent variable significantly linked to decreased risk for long‐term complications due to inadequate immunosuppression (odds ratio [OR]: 0.27 [0.09–0.77]; p = 0.019). Our data suggest that the longitudinal monitoring of TTV DNAemia in kidney transplant recipients could help preventing the long‐term complications due to inadequate immunosuppression. [ABSTRACT FROM AUTHOR]

Context Sex-specific prevalence and incidence of type 2 diabetes (T2D) have been reported, but the underlying mechanisms are uncertain. Objective In this study, we aimed to investigate whether iron biomarkers mediate the association between biological sex and glucose metabolism and the incidence of T2D. Methods We used data from the general population enrolled in the prospective Prevention of REnal and Vascular ENd-stage Disease study in Groningen, The Netherlands. We measured ferritin, transferrin saturation (TSAT), hepcidin, soluble transferrin receptor (sTfR), fasting plasma glucose (FPG), fasting plasma insulin (FPI) levels, and incidence of T2D. We used multivariable regression and mediation analyses to investigate our hypothesis. All iron biomarkers, FPG, and FPI were log-transformed. Results The mean (SD) age of the 5312 (51.3% female) individuals was 52.2 (11.6) years. Compared with males, females had lower FPG (β = −.01; 95% CI −0.02, −0.01) and FPI (β = −.03; 95% CI −0.05, −0.02) levels. Ferritin, hepcidin, and sTfR showed potential mediating effects on the association between sex and FPG, 21%, 5%, and 7.1%, respectively. Furthermore, these variables mediated 48.6%, 5.7%, and 3.1% of the association between sex and FPI, respectively. Alternatively, TSAT had a suppressive mediating role in the association of sex with FPG and FPI. The incidence of T2D was lower in females than in males (hazard ratio 0.58; 95% CI 0.44, 0.77), with 19.2% of this difference being mediated by ferritin. Conclusion Iron biomarkers may partially mediate the association between sex and glucose homeostasis. Future studies addressing the causality of our findings are needed. [ABSTRACT FROM AUTHOR]

Liver transplant recipients (LTRs) have lower long-term survival rates compared with the general population. This underscores the necessity for developing biomarkers to assess post-transplantation mortality. Here we compared plasma trimethylamine-N-oxide (TMAO) levels with those in the general population, investigated its determinants, and interrogated its association with all-cause mortality in stable LTRs. Plasma TMAO was measured in 367 stable LTRs from the TransplantLines cohort (NCT03272841) and in 4837 participants from the population-based PREVEND cohort. TMAO levels were 35% higher in LTRs compared with PREVEND participants (4.3 vs. 3.2 µmol/L, p < 0.001). Specifically, TMAO was elevated in LTRs with metabolic dysfunction-associated steatotic liver disease, alcohol-associated liver disease, and polycystic liver disease as underlying etiology (p < 0.001 for each). Among LTRs, TMAO levels were independently associated with eGFR (std. β = −0.43, p < 0.001) and iron supplementation (std. β = 0.13, p = 0.008), and were associated with mortality (29 deaths during 8.6 years follow-up; log-rank test p = 0.017; hazard ratio of highest vs. lowest tertile 4.14, p = 0.007). In conclusion, plasma TMAO is likely elevated in stable LTRs, with impaired eGFR and iron supplementation as potential contributory factors. Our preliminary findings raise the possibility that plasma TMAO could contribute to increased mortality risk in such patients, but this need to be validated through a series of rigorous and methodical studies. [ABSTRACT FROM AUTHOR]

Background Dysregulated energy metabolism is a recently discovered key feature of autosomal dominant polycystic kidney disease (ADPKD). Cystic cells depend on glucose and are poorly able to use other energy sources such as ketone bodies. Raising ketone body concentration reduced disease progression in animal models of polycystic kidney diseases. Therefore, we hypothesized that higher endogenous plasma beta-hydroxybutyrate (BHB) concentrations are associated with reduced disease progression in patients with ADPKD. Methods We analyzed data from 670 patients with ADPKD participating in the Developing Intervention Strategies to Halt Progression of ADPKD (DIPAK) cohort, a multi-center prospective observational cohort study. BHB was measured at baseline using nuclear magnetic resonance spectroscopy. Participants were excluded if they had type 2 diabetes, were using disease-modifying drugs (e.g. tolvaptan, somatostatin analogs), were not fasting or had missing BHB levels, leaving 521 participants for the analyses. Linear regression analyses were used to study cross-sectional associations and linear mixed-effect modeling for longitudinal associations. Results Of the participants, 61% were female, with an age of 47.3 ± 11.8 years, a height-adjusted total kidney volume (htTKV) of 834 [interquartile range (IQR) 495–1327] mL/m and an estimated glomerular filtration rate (eGFR) of 63.3 ± 28.9 mL/min/1.73 m2. The median concentration of BHB was 94 (IQR 68–147) µmol/L. Cross-sectionally, BHB was associated neither with eGFR nor with htTKV. Longitudinally, BHB was positively associated with eGFR slope {B = 0.35 mL/min/1.73 m2 [95% confidence interval (CI) 0.09 to 0.61], P  = .007}, but not with kidney growth. After adjustment for potential confounders, every doubling in BHB concentration was associated with an improvement in the annual rate of eGFR by 0.33 mL/min/1.73 m2 (95% CI 0.09 to 0.57, P  = .008). Conclusion These observational analyses support the hypothesis that interventions that raise BHB concentration could reduce the rate of kidney function decline in patients with ADPKD. [ABSTRACT FROM AUTHOR]

Objective This work aimed to study whether fibroblast growth factor 23 (FGF23) is predictive for incident posttransplant diabetes mellitus (PTDM) in kidney transplant recipients (KTRs). Methods We repeatedly analyzed plasma C-terminal FGF23 concentrations in 170 KTRs enrolled in the TransplantLines Biobank and Cohort Study. Associations of time-updated plasma FGF23 with incident PTDM were studied by Cox regression. Results A total of 170 KTRs (46% female, aged 54.4 ± 12.4 years) with 540 FGF23 measurements were included. Plasma FGF23 concentrations at transplantation were 31.1 (0.76-2576) pmol/L. During a follow-up of 24 (12-24) months, 38 patients developed PTDM. The highest FGF23 tertile (compared to the lowest) was associated with an increased risk for PTDM (fully adjusted hazard ratio 20.9; 95% CI, 3.4-130.0; P <.001). Conclusion In KTRs without diabetes at baseline, the highest tertile of FGF23, compared to the lowest, is predictive for development of PTDM. [ABSTRACT FROM AUTHOR]

Kidney transplantation is the best treatment for kidney failure in older patients. However, little is known regarding changes in health-related quality of life (HRQoL) from before to after transplantation and determinants of HRQoL in older kidney transplant recipients (KTR). We studied both, using data of older (≥65 years) patients waitlisted for kidney transplantation and older KTR 1 year after transplantation from the TransplantLines Biobank and Cohort Study. HRQoL was assessed using the SF-36 questionnaire. We included 145 older waitlisted patients (68% male, age 70 ± 4 years) and 115 older KTR at 1 year after transplantation (73% male, age 70 ± 4 years). Both mental (48.5 ± 8.4 versus 51.2 ± 7.7, p = 0.009) and physical (47.4 ± 8.5 versus 52.1 ± 7.2, p < 0.001) HRQoL were higher among included KTR, compared to the waitlisted patients. In paired analyses among 46 patients with HRQoL-data both before and after transplantation, there was a trend towards increased mental HRQoL (49.1 ± 8.4 to 51.6 ± 7.5, p = 0.054), and significantly increased physical HRQoL (48.1 ± 8.0 to 52.4 ± 6.7, p = 0.001) after transplantation. Among all assessed factors, the number of patient-reported immunosuppressive drug-related side effects was most strongly negatively associated with both mental and physical HRQoL. In conclusion, HRQoL is significantly higher among older KTR after kidney transplantation compared to older waitlisted patients. [ABSTRACT FROM AUTHOR]

Background: Heart failure (HF) features a shift in metabolism towards enhanced utilization of ketone bodies. While elevations in plasma natriuretic peptides represent a biochemical hallmark of HF, natriuretic peptides may promote lipolysis, thereby contributing to fatty acid availability for ketogenesis. Methods: We cross-sectionally tested to what extent fasting plasma total ketone bodies (measured using nuclear magnetic resonance spectroscopy) are associated with N-terminal pro-BNP (NT-proBNP; electrochemiluminescent sandwich immunoassay) in individuals with and without HF. Results: Among 6217 participants from the Prevention of REnal and Vascular ENd-stage Disease (PREVEND) study, 203 were identified with HF. NT-proBNP was four-fold and total ketone bodies were 25% higher in HF participants (each p < 0.001). In both participants with and without HF, total ketone body levels correlated with NT-proBNP (r = 0.116 and 0.185, respectively; p < 0.001). In multivariable linear regression analysis adjusted for relevant covariates, total ketone bodies remained associated with NT-proBNP in the whole cohort (std β = 0.08, p < 0.001), without a difference in participants with and without HF (p interaction: 0.52). Conclusion: This general population-based study reveals an independent association of fasting total body ketone bodies with plasma NT-proBNP. Our findings suggest that a metabolic defense mechanism could be operative, providing the myocardium with ketone bodies to meet its energy demands. [ABSTRACT FROM AUTHOR]

Objective: The study objective was to examine associations of relative fat mass (RFM) and BMI with all‐cause mortality in the Dutch general population and to investigate whether additional adjustment for muscle mass strengthened these associations. Methods: A total of 8433 community‐dwelling adults from the PREVEND general population cohort (1997–1998) were included. Linear regression models were used to examine associations of RFM and BMI with 24‐h urinary creatinine excretion, a marker of total muscle mass. Cox regression models were used to examine associations of RFM and BMI with all‐cause mortality. Results: The mean age of the cohort was 49.8 years (range: 28.8–75.7 years), and 49.9% (n = 4209) were women. In age‐ and sex‐adjusted models, both RFM and BMI were associated with total muscle mass (24‐h urinary creatinine excretion), and these associations were stronger with BMI (standardized beta [Sβ]RFM: 0.29; 95% CI: 0.27–0.31 vs. SβBMI: 0.38; 95% CI: 0.36–0.40; pdifference < 0.001). During a median follow‐up period of 18.4 years, 1640 deaths (19.4%) occurred. In age‐ and sex‐adjusted models, RFM was significantly associated with all‐cause mortality (hazard ratio per 1‐SD [HRRFM]: 1.16; 95% CI: 1.09–1.24), whereas BMI was not (HRBMI: 1.04; 95% CI: 0.99–1.10). After additional adjustment for muscle mass, associations of both RFM and BMI with all‐cause mortality increased in magnitude (HRRFM: 1.24; 95% CI: 1.16–1.32 and HRBMI: 1.12; 95% CI: 1.06–1.19). Results were broadly similar in multivariable adjusted models. Conclusions: In the general population, a higher RFM was significantly associated with mortality risk, whereas a higher BMI was not. Adjusting for total muscle mass increased the strength of associations of both RFM and BMI with all‐cause mortality. [ABSTRACT FROM AUTHOR]

Background: In the ageing population, issues with bone and joint health are highly prevalent. Both beneficial and potential risks of dairy products on bone and joint health are reported in epidemiological studies. Furthermore, the phosphorus (P) load from dairy could potentially lead to unfavorable changes in P metabolism. Objective: To investigate the effect of dairy intake on markers of bone and joint metabolism and P metabolism in an intervention study with high and low dairy intake. Methods: In a post hoc analysis of a randomized cross-over trial with overweight adults, the effect of a standardized high dairy intake [HDI (5–6 dairy portions per day) versus low dairy intake (LDI, ≤ 1 dairy portion/day)] for 6 weeks on markers of bone and joint health was assessed using enzyme-linked immunosorbent assays and electrochemiluminescence immunoassays. Markers indicative for cartilage breakdown, including urinary CTX-II, serum COMP and 4-hydroxyproline, and markers indicative for bone remodeling, such as serum CTX-I, PTH, 25(OH)D, osteocalcin, P1NP and FGF23, were investigated using linear mixed models. Furthermore, changes in P metabolism, including the main phosphate-regulating hormone FGF23 were explored. Results: This study was completed by 46 adults (57% female, age 59 ± 4 years, BMI 28 ± 2 kg/m2). Following HDI, markers such as urinary CTX-II excretion, COMP, 25(OH)D, PTH and CTX-I were significantly lower after HDI, as compared to LDI. For example, CTX-II excretion was 1688 ng/24 h at HDI, while it was 2050 ng/24 h at LDI (p < 0.001). Concurrently, P intake was higher at HDI than at LDI (2090 vs 1313 mg/day, p < 0.001). While plasma P levels did not differ (1.03 vs 1.04 mmol/L in LDI, p = 0.36), urinary P excretion was higher at HDI than at LDI (31 vs 28 mmol/L, p = 0.04). FGF23 levels tended to be higher at HDI than at LDI (76.3 vs. 72.9 RU/mL, p = 0.07). Conclusions: HDI, as compared to LDI, reduced markers that are indicative for joint and bone resorption and bone turnover. No changes in P metabolism were observed. Clinical trial registry: This trial was registered at https://trialsearch.who.int/Trial2.aspx?TrialID=NTR4899 as NTR4899. [ABSTRACT FROM AUTHOR]

Purpose: We investigated the associations of socioeconomic position (SEP) with total and type of fish intake in a large general population and validated whether types of fish intake were differently associated with plasma EPA and DHA in a subset of the population. Methods: From the Lifelines Cohort Study, 94,246 participants aged 44 ± 13 years old were included to test the association of two SEP indicators, i.e., education level and household income level, with dietary intakes of total, oily, lean, fried, and other types of fish. In a subset of 575 participants (mean age: 50 ± 13 years), EPA and DHA levels were measured in plasma phospholipids and triglycerides. Dietary fish intake was assessed using Food Frequency Questionnaire. Linear regressions were applied and adjusted for relevant covariates. Results: Compared to the high education level, lower education levels were negatively associated with total, oily, lean, and other fish intake (p < 0.001 for all), and positively associated with fried fish intake (β (SE): 0.04 (0.04), p < 0.001 for middle education; 0.07 (0.04), p < 0.001 for low education), independently of relevant covariates. Similar results were observed for income levels. In the subset population, total and oily fish intakes were positively associated with plasma EPA and DHA (p < 0.02 for all). Lean and other fish intakes were positively associated with only DHA (p < 0.008 for all), but not EPA, while fried fish was not associated with either EPA or DHA in plasma (p > 0.1 for all). Conclusion: Lower SEP was associated with a lower total intake of fish, and of oily and lean fish, but with higher intake of fried fish. Fried fish was not associated with the fish-based EPA and DHA in plasma. Hence, SEP-related differences in fish consumption are both quantitative and qualitative. [ABSTRACT FROM AUTHOR]

The impact of pre-transplant parathyroid hormone (PTH) levels on early or long-term kidney function after kidney transplantation is subject of debate. We assessed whether severe hyperparathyroidism is associated with delayed graft function (DGF), deathcensored graft failure (DCGF), or all-cause mortality. In this single-center cohort study, we studied the relationship between PTH and other parameters related to bone and mineral metabolism, including serum alkaline phosphatase (ALP) at time of transplantation with the subsequent risk of DGF, DCGF and all-cause mortality using multivariable logistic and Cox regression analyses. In 1,576 kidney transplant recipients (51.6 ± 14.0 years, 57.3% male), severe hyperparathyroidism characterized by pre-transplant PTH ≥771 pg/ mL (>9 times the upper limit) was present in 121 patients. During 5.2 [0.2--30.0] years follow-up, 278 (15.7%) patients developed DGF, 150 (9.9%) DCGF and 432 (28.6%) died. A higher pre-transplant PTH was not associated with DGF (HR 1.06 [0.90--1.25]), DCGF (HR 0.98 [0.87--1.13]), or all-cause mortality (HR 1.02 [0.93--1.11]). Results were consistent in sensitivity analyses. The same applied to other parameters related to bone and mineral metabolism, including ALP. Severe pre-transplant hyperparathyroidism was not associated with an increased risk of DGF, DCGF or all-cause mortality, not supporting the need of correction before kidney transplantation to improve graft or patient survival. [ABSTRACT FROM AUTHOR]

Pharmaceutical polymers and excipients represent interesting but often overlooked chemical classes in clinical exposure and bioanalytical research. These chemicals may cause hypersensitivity reactions, they can be useful to confirm exposure to pharmaceuticals, and they may pose bioanalytical challenges, including ion suppression in liquid chromatography-mass spectrometry (LC-MS-)based workflows. In this work, we assessed these chemicals in light of a rather surprising finding presented in two previously published studies, namely that usage of cyclosporine A, an immunosuppressive drug which is known to be cleared through excretion in the bile, explained the largest amount of variance in principal component analysis of urinary LC-SWATH/MS small-molecule profiling data. Specifically, we examined the freely-accessible 24-hour urine metabolomics data of 570 kidney transplant recipients included in the TransplantLines Biobank and Cohort Study (NCT03272841). These data unveiled thousands of high-abundance polymer peaks in some samples, which were associated with the use of the macrogol (i.e., polyethylene glycol) 3350 oral laxative agent. In addition, we found multiple clusters of high-abundance peaks which were linked to the exposure to two pharmaceutical excipients, namely short-chain polyethylene glycol (molecular weight <1000 Da) and polyethoxylated castor oil (also known as Kolliphor® EL or Cremophor® EL). Respectively, these excipients are used in temazepam capsules and cyclosporine A capsules, and the latter provides a plausible explanation for the rather surprising finding that instigated our work. Moreover, such explanation and our findings in general put emphasis on taking into consideration these and other pharmaceutical polymers and excipients when exploring, processing, and interpreting clinical small-molecule profiling data. [ABSTRACT FROM AUTHOR]

The associations of HDL particle (HDL-P) and subspecies concentrations with alcohol consumption are unclear. We aimed to evaluate the interplay between alcohol consumption, HDL parameters and cardiovascular disease (CVD) risk. In the PREVEND study of 5151 participants (mean age, 53 years; 47.5% males), self-reported alcohol consumption and HDL-P and subspecies (small, medium, and large) by nuclear magnetic resonance spectroscopy were assessed. Hazard ratios (HRs) with 95% CIs for first CVD events were estimated. In multivariable linear regression analyses, increasing alcohol consumption increased HDL-C, HDL-P, large and medium HDL, HDL size, and HDL subspecies (H3P, H4P, H6 and H7) in a dose-dependent manner. During a median follow-up of 8.3 years, 323 first CVD events were recorded. Compared with abstainers, the multivariable adjusted HRs (95% CIs) of CVD for occasional to light, moderate, and heavy alcohol consumers were 0.72 (0.55–0.94), 0.74 (0.54–1.02), and 0.65 (0.38–1.09), respectively. These associations remained consistent on additional adjustment for each HDL parameter. For CVD, only HDL-C was associated with a statistically significant decreased risk of CVD in a fully adjusted analysis (HR 0.84, 95% CI 0.72–0.97 per 1 SD increment). For coronary heart disease, HDL-C, HDL-P, medium HDL, HDL size, and H4P showed inverse associations, whereas HDL-C and HDL size modestly increased stroke risk. Except for H6P, alcohol consumption did not modify the associations between HDL parameters and CVD risk. The addition of HDL-C, HDL size, or H4P to a CVD risk prediction model containing established risk factors improved risk discrimination. Increasing alcohol consumption is associated with increased HDL-C, HDL-P, large and medium HDL, HDL size, and some HDL subspecies. Associations of alcohol consumption with CVD are largely independent of HDL parameters. The associations of HDL parameters with incident CVD are generally not attenuated or modified by alcohol consumption. [ABSTRACT FROM AUTHOR]

We investigated whether urinary vascular non-inflammatory molecule-1 (vanin-1), a promising early-onset tubular injury marker, correlates with other established tubular injury markers and is associated with graft failure in kidney transplant recipients (KTR). We measured 24 h urinary vanin-1 excretion in 656 KTR (age 53 ± 13 years, 43% female, estimated glomerular filtration rate (eGFR) 53 ± 21 mL/min/1.73 m2) who had undergone kidney transplantation ≥ 1 year. The median 24 h urinary vanin-1 excretion was 145 [51–331] pmol/24 h. 24 h urinary vanin-1 excretion correlated weakly but significantly with other tubular injury markers (ρ = 0.14, p < 0.001 with urinary liver-type fatty acid binding protein, ρ = 0.13, p = 0.001 with urinary post-translationally modified fetuin-A protein, and ρ = 0.10, p = 0.011 with plasma neutrophil gelatinase-associated lipocalin) and with eGFR (ρ = − 0.13, p = 0.001). During a median follow-up of 7.4 [4.9–8.0] years, 94 (14%) KTR developed death-censored graft failure. In multivariable Cox regression analyses, 24 h urinary vanin-1 excretion was not associated with an increased risk of death-censored graft failure (adjusted hazard ratio [95% confidence interval] = 0.96 [0.86–1.07], p = 0.5). In conclusion, our findings do not support the role of urinary vanin-1 as a biomarker of graft failure after kidney transplantation. [ABSTRACT FROM AUTHOR]

Background Fatigue and impaired health-related quality of life (HRQoL) are common among kidney transplant recipients (KTR). We hypothesized that both may partially be attributable to poor sleep. Methods Cross-sectional and longitudinal data of KTR enrolled in the TransplantLines Biobank and Cohort Study were used. Sleep quality was assessed using the Pittsburgh Sleep Quality Index questionnaire. Individual strength (i.e. a composite of fatigue, concentration, motivation and physical activity), societal participation and HRQoL were assessed using validated questionnaires. Results We included 872 KTR (39% female, age 56 ± 13 years) and 335 healthy controls. In total, 33% of male KTR and 49% of female KTR reported poor sleep quality, which was higher compared with male and female healthy controls (19% and 28%, respectively, P  < .001 for both). In logistic regression analyses, female sex, anxiety, active smoking, low protein intake, physically inactive lifestyle, low plasma magnesium concentration, using calcineurin inhibitors, not using mTOR inhibitors and using benzodiazepine agonists were associated with poor sleep quality. In adjusted linear regression analyses, poor sleep was strongly and independently associated with lower individual strength [standardized β (st.β) = 0.59, 95% confidence interval (CI) 0.45 to 0.74, P  < .001], poorer societal participation (frequency: st.β = −0.17, 95% CI −0.32 to −0.01, P  = .04; restrictions: st.β = −0.36, 95% CI −0.51 to −0.21, P  < .001; satisfaction: st.β = −0.44, 95% CI −0.59 to −0.28, P  < .001) and lower HRQoL (physical: st.β = −0.53, 95% CI −0.68 to −0.38, P  < .001; mental: st.β = −0.64, 95% CI −0.78 to −0.50, P  < .001). The associations with poorer societal participation and lower HRQoL were strongly mediated by individual strength (P  < .001 for all), yet the suggested direct effects of poor sleep quality on HRQoL remained significant (P physical = .03, P mental = .002). Longitudinal data of 292 KTR showed that sleep quality improves after kidney transplantation in males (P  < .001), but not in females (P  = .9). Conclusions Poor sleep quality is common among KTR, and may be a potential target to improve fatigue, societal participation and HRQoL among KTR. [ABSTRACT FROM AUTHOR]

This article examines the relationship between albuminuria (a marker of chronic kidney disease) and the occurrence of cancer. The study analyzes data from a Dutch population-based cohort and identifies potential factors that explain the connection between albuminuria and cancer. The researchers find that markers of systemic inflammation, oxidative stress, and kidney function partially mediate the association between albuminuria and overall cancer incidence. The study provides valuable insights into the mechanisms linking albuminuria and cancer, suggesting that inflammation may play a role in cancer development in individuals with albuminuria. Further research is needed to explore other potential factors and pathways. [Extracted from the article]

Torque teno virus (TTV) is emerging as a potential marker for monitoring immune status. In transplant recipients who are immunosuppressed, higher TTV DNA loads are observed than in healthy individuals. TTV load measurement may aid in optimizing immunosuppressive medication dosing in solid organ transplant recipients. Additionally, there is a growing interest in the role of HDL particles in immune function; therefore, assessment of both HDL concentrations and TTV load may be of interest in transplant recipients. The objective of this study was to analyze TTV loads and HDL parameters in serum samples collected at least one year post-transplantation from 656 stable outpatient kidney transplant recipients (KTRs), enrolled in the TransplantLines Food and Nutrition Cohort (Groningen, the Netherlands). Plasma HDL particles and subfractions were measured using nuclear magnetic resonance spectroscopy. Serum TTV load was measured using a quantitative real-time polymerase chain reaction. Associations between HDL parameters and TTV load were examined using univariable and multivariable linear regression. The median age was 54.6 [IQR: 44.6 to 63.1] years, 43.3% were female, the mean eGFR was 52.5 (±20.6) mL/min/1.73 m2 and the median allograft vintage was 5.4 [IQR: 2.0 to 12.0] years. A total of 539 participants (82.2%) had a detectable TTV load with a mean TTV load of 3.04 (±1.53) log10 copies/mL, the mean total HDL particle concentration was 19.7 (±3.4) μmol/L, and the mean HDL size was 9.1 (±0.5) nm. The univariable linear regression revealed a negative association between total HDL particle concentration and TTV load (st.β = −0.17, 95% CI st.β: −0.26 to −0.09, p < 0.001). An effect modification of smoking behavior influencing the association between HDL particle concentration and TTV load was observed (Pinteraction = 0.024). After adjustment for age, sex, alcohol intake, hemoglobin, eGFR, donor age, allograft vintage and the use of calcineurin inhibitors, the negative association between HDL particle concentration and TTV load remained statistically significant in the non-smoking population (st.β = −0.14, 95% CI st.β: −0.23 to −0.04, p = 0.006). Furthermore, an association between small HDL particle concentration and TTV load was found (st.β = −0.12, 95% CI st.β: −0.22 to −0.02, p = 0.017). Higher HDL particle concentrations were associated with a lower TTV load in kidney transplant recipients, potentially indicative of a higher immune function. Interventional studies are needed to provide causal evidence on the effects of HDL on the immune system. [ABSTRACT FROM AUTHOR]

Metformin (N,N-dimethylbiguanide), an inhibitor of gluconeogenesis and insulin sensitizer, is widely used for the treatment of type 2 diabetes. In some patients with renal insufficiency, metformin can accumulate and cause lactic acidosis, known as metformin-associated lactic acidosis (MALA, defined as lactate ≥ 5 mM, pH < 7.35, and metformin concentration > 38.7 µM). Here, we report on the post-translational modification (PTM) of proline (Pro) to 4-hydroxyproline (OH-Pro) in metformin-associated lactic acidosis and in metformin-treated patients with Becker muscular dystrophy (BMD). Pro and OH-Pro were measured simultaneously by gas chromatography–mass spectrometry before, during, and after renal replacement therapy in a patient admitted to the intensive care unit (ICU) because of MALA. At admission to the ICU, plasma metformin concentration was 175 µM, with a corresponding lactate concentration of 20 mM and a blood pH of 7.1. Throughout ICU admission, the Pro concentration was lower compared to healthy controls. Renal excretion of OH-Pro was initially high and decreased over time. Moreover, during the first 12 h of ICU admission, OH-Pro seems to be renally secreted while thereafter, it was reabsorbed. Our results suggest that MALA is associated with hyper-hydroxyprolinuria due to elevated PTM of Pro to OH-Pro by prolyl-hydroxylase and/or inhibition of OH-Pro metabolism in the kidneys. In BMD patients, metformin, at the therapeutic dose of 3 × 500 mg per day for 6 weeks, increased the urinary excretion of OH-Pro suggesting elevation of Pro hydroxylation to OH-Pro. Our study suggests that metformin induces specifically the expression/activity of prolyl-hydroxylase in metformin intoxication and BMD. [ABSTRACT FROM AUTHOR]

Introduction: There is a great clinical need for novel markers to predict kidney function decline in patients with type 2 diabetes. We explored the potential of posttranslationally modified fetuin-A fragments in urine (uPTM-FetA) as such a marker. Methods: We included patients with type 2 diabetes from two independent, nonoverlapping prospective cohort studies. A cut-off for uPTM-FetA, measured via ELISA method, was determined using the Youden index in the primary cohort of patients with type 2 diabetes from Taiwan. Kidney endpoint was defined as an estimated glomerular filtration rate (eGFR) decline ≥30% from baseline, reaching of an eGFR <15 mL/min/1.73 m2, or a need of renal replacement therapy. Prospective associations were assessed in Cox regression models. All analyses were replicated in a cohort of patients with type 2 diabetes from the Netherlands. Results: In total, 294 patients with type 2 diabetes (age 61 ± 10 years, 55% male, eGFR 88 ± 16 mL/min/1.73 m2) were included in the primary cohort. During a follow-up of median 4.6 years, 42 participants (14%) experienced the kidney endpoint. Using the defined cut-off, a high uPTM-FetA was associated with a higher risk of renal function decline (Plog-rank < 0.0001). This association was similar in subgroups depending on albuminuria. This association remained, independent of age, sex, baseline eGFR, albuminuria, HbA1c, and other potential confounders (HR: 9.94; 95% CI: 2.96–33.40; p < 0.001 in the final model). Analyses in the validation cohort (376 patients with type 2 diabetes, age 64 ± 11 years, 66% male, eGFR 76 ± 24 mL/min/1.73 m2) using the same cut-off yielded similar results. Conclusion: uPTM-FetA was independently associated with kidney function decline in patients with type 2 diabetes validated in a 2-cohort study. The significant additive predictive power of this biomarker from conventional risk factors suggests its clinical use for renal function progression in patients with type 2 diabetes. [ABSTRACT FROM AUTHOR]

Background Chronic kidney disease (CKD) is believed to be associated with an increased risk for cancer, especially urinary tract cancer. However, previous studies predominantly focused on the association of decreased estimated glomerular filtration rate (eGFR) with cancer. In this study, we investigated the association of albuminuria with cancer incidence, adjusted for eGFR. Methods We included 8490 subjects in the Prevention of Renal and Vascular End-stage Disease (PREVEND) observational study. Urinary albumin excretion (UAE) was measured in two 24-hour urine specimens at baseline. Primary outcomes were the incidence of overall and urinary tract cancer. Secondary outcomes were the incidence of other site-specific cancers, and mortality due to overall, urinary tract, and other site-specific cancers. Results Median baseline UAE was 9.4 (IQR, 6.3–17.8) mg/24 h. During a median follow-up of 17.7 years, 1341 subjects developed cancer (of which 177 were urinary tract cancers). After multivariable adjustment including eGFR, every doubling of UAE was associated with a 6% (hazard ratios (HR), 1.06, 95% confidence intervals (CI), 1.02–1.10), and 14% (HR, 1.14, 95% CI, 1.04–1.24) higher risk of overall and urinary tract cancer incidence, respectively. Except for lung and hematological cancer, no associations were found between UAE and the incidence of other site-specific cancer. Doubling of UAE was also associated with a higher risk of mortality due to overall and lung cancer. Conclusions Higher albuminuria is associated with a higher incidence of overall, urinary tract, lung, and hematological cancer, and with a higher risk of mortality due to overall and lung cancers, independent of baseline eGFR. [ABSTRACT FROM AUTHOR]

Background: Insulin resistance plays an important role in the development of post-transplantation diabetes mellitus (PTDM) in kidney transplant recipients (KTRs). Current methods for the direct determination of insulin resistance are complicated and invasive. Therefore, this study aimed to investigate the relevance of indirect insulin resistance indices in relation to the development of PTDM in KTRs. Methods: We included 472 stable outpatient KTRs without diabetes at baseline from a prospective cohort study. Four indirect insulin resistance indices, namely homeostasis model assessment–insulin resistance (HOMA-IR), visceral adiposity index (VAI), lipid accumulation product (LAP), and triglycerides–glucose (TyG) index, were assessed. We analyzed each measure using the receiver operating characteristic (ROC) curve for PTDM development. The optimal cut-off value for each parameter was determined using the Youden index. Results: After a median of 9.6 years (interquartile range (IQR) 6.6–10.2) of follow-up, 68 (14%) KTRs developed PTDM. In Cox regression analyses, all indirect insulin resistance indices associated with incident PTDM were independent of potential confounders. ROC curve was 0.764 (95% CI, 0.703–0.826) for HOMA-IR, 0.685 (95% CI, 0.615–0.757) for VAI, 0.743 (95% CI, 0.678–0.808) for LAP, and 0.698 (95% CI, 0.629–0.766) for TyG index, with respective optimal cut-off values of 2.47, 4.01, 87.0, and 4.94. Conclusions: Indirect insulin resistance indices can be used to predict incident PTDM in KTRs. In addition to HOMA-IR, insulin-free surrogates of insulin resistance might serve as useful methods to identify KTRs at risk of PTDM, thus obviating the necessity to measure insulin. [ABSTRACT FROM AUTHOR]

Torque Teno Virus (TTV) is a non-pathogenic virus that is highly prevalent among kidney transplant recipients (KTRs). Its circulating load is associated with an immunological status in KTR and is considered a promising tool for guiding immunosuppression. To allow for optimal guidance, it is important to identify other determinants of TTV load. We aimed to investigate the potential association of smoking and alcohol intake with TTV load. For this cross-sectional study, serum TTV load was measured using PCR in stable kidney transplant recipients at ≥1 year after transplantation, and smoking status and alcohol intake were assessed through questionnaires and measurements of urinary cotinine and ethyl glucuronide. A total of 666 KTRs were included (57% male). A total of 549 KTR (82%) had a detectable TTV load (3.1 ± 1.5 log10 copies/mL). In KTR with a detectable TTV load, cyclosporin and tacrolimus use were positively associated with TTV load (St. β = 0.46, p < 0.001 and St. β = 0.66, p < 0.001, respectively), independently of adjustment for potential confounders. Current smoking and alcohol intake of >20 g/day were negatively associated with TTV load (St. β = −0.40, p = 0.004 and St. β = −0.33, p = 0.009, respectively), independently of each other and of adjustment for age, sex, kidney function, time since transplantation and calcineurin inhibitor use. This strong association of smoking and alcohol intake with TTV suggests a need to account for the smoking status and alcohol intake when applying TTV guided immunosuppression in KTR. [ABSTRACT FROM AUTHOR]

We studied the role of adherence to antihypertensive drug therapy (AHT) in blood pressure (BP) control in a type 2 diabetes (T2D) population treated in secondary care in the DIAbetes and LifEstyle Cohort Twente-1 (DIALECT-1). In addition, intensification of AHT was assessed. Adherence was determined by using the medication possession ratio (MPR), calculated with pharmacy dispensing data for a period of two years following baseline. Adherence was defined as an MPR ≥ 80%. The proportion of adherent patients was compared between patients who had BP-on target (BP-OT) and BP-not on target (BP-NOT). Of the 385 patients included, 56% achieved their BP target. The proportion of adherent patients did not differ between BP-OT and BP-NOT (96% vs. 96%; p = 0.91). Intensification of AHT, including 'increase in dosage' and 'start of a new drug', was assessed in the two years following baseline. In only 37% of patients with uncontrolled BP during follow-up was AHT intensified. To conclude, adherence to AHT was high and there does not seem to be a relationship between adherence and BP control. There is an opportunity to improve AHT in patients who do not reach their BP target. [ABSTRACT FROM AUTHOR]

Background: In the Netherlands, more than one million patients have type 2 diabetes (T2D), and approximately 36% of these patients have chronic kidney disease (CKD). Yearly medical costs related to T2D and CKD account for approximately €1.3 billion and €805 million, respectively. The FIDELIO-DKD trial showed that the addition of finerenone to the standard of care (SoC) lowers the risk of CKD progression and cardiovascular (CV) events in patients with CKD stages 2–4 associated with T2D. This study investigates the cost-effectiveness of adding finerenone to the SoC of patients with advanced CKD and T2D compared to SoC monotherapy. Methods: The validated FINE-CKD model is a Markov cohort model which simulates the disease pathway of patients over a lifetime time horizon. The model was adapted to reflect the Dutch societal perspective. The model estimated the incremental costs, utilities, and incremental cost-effectiveness ratio (ICER). Sensitivity and scenario analyses were performed to assess the effect of parameter uncertainty on model robustness. Results: When used in conjunction with SoC, finerenone extended time free of CV events and renal replacement therapy by respectively 0.30 and 0.31 life years compared to SoC alone, resulting in an extension of 0.20 quality-adjusted life years (QALYs). The reduction in renal and CV events led to a €6136 decrease in total lifetime costs per patient compared to SoC alone, establishing finerenone as a dominant treatment option. Finerenone in addition to SoC had a 83% probability of being dominant and a 93% probability of being cost-effective at a willingness-to-pay threshold of €20,000. Conclusion: By reducing the risk of CKD progression and CV events, finerenone saves costs to society while gaining QALYs in patients with T2D and advanced CKD in the Netherlands. [ABSTRACT FROM AUTHOR]

Background The identification of new biomarkers in autosomal-dominant polycystic kidney disease (ADPKD) is crucial to improve and simplify prognostic assessment as a basis for patient selection for targeted therapies. Post hoc analyses of the TEMPO 3:4 study indicated that copeptin could be one of those biomarkers. Methods Copeptin was tested in serum samples from patients of the AD(H)PKD study. Serum copeptin levels were measured using a time-resolved amplified cryptate emission (TRACE)-based assay. In total, we collected 711 values from 389 patients without tolvaptan treatment and a total of 243 values (of which 64 were pre-tolvaptan) from 94 patients on tolvaptan. These were associated with rapid progression and disease-causing gene variants and their predictive capacity tested and compared with the Mayo Classification. Results As expected, copeptin levels showed a significant negative correlation with estimated glomerular filtration rate (eGFR). Measurements on tolvaptan showed significantly higher copeptin levels (9.871 pmol/L vs 23.90 pmol/L at 90/30 mg; P  < .0001) in all chronic kidney disease stages. Linear regression models (n  = 133) show that copeptin is an independent predictor of eGFR slope. A clinical model (including eGFR, age, gender, copeptin) was nearly as good (R2 = 0.1196) as our optimal model (including height-adjusted total kidney volume, eGFR, copeptin, R2 = 0.1256). Adding copeptin to the Mayo model improved future eGFR estimation. Conclusion Copeptin levels are associated with kidney function and independently explained future eGFR slopes. As expected, treatment with tolvaptan strongly increases copeptin levels. [ABSTRACT FROM AUTHOR]

Background: Non-alcoholic fatty liver disease (NAFLD) is a common liver disease increasing cardiovascular disease (CVD) morbidity and mortality. Autoantibodies against apolipoprotein A-1 (AAA-1) are a possible novel CVD risk factor promoting inflammation and disrupting cellular lipid homeostasis, two prominent pathogenic features of NAFLD. We explored the role of AAA-1 in NAFLD and their association with CVD risk. Methods: HepaRG cells and liver sections from ApoE−/− mice exposed to AAA-1 were used for lipid quantification and conditional protein expression. Randomly selected sera from 312 subjects of the Prevention of Renal and Vascular End-stage Disease (PREVEND) general population cohort were used to measure AAA-1. A Fatty Liver Index (FLI) ≥ 60 and a 10-year Framingham Risk Score (FRS) ≥ 20% were used as proxy of NAFLD and high CVD risk, respectively. Results: In-vitro and mouse models showed that AAA-1 increased triglyceride synthesis leading to steatosis, and promoted inflammation and hepatocyte injury. In the 112 PREVEND participants with FLI ≥ 60, AAA-1 were associated with higher FRS, alkaline phosphatase levels, lower HDL cholesterol and tended to display higher FLI values. Univariate linear and logistic regression analyses (LRA) confirmed significant associations between AAA-1, FLI and FRS ≥ 20%, while in adjusted LRA, FLI was the sole independent predictor of FRS ≥ 20% (OR: 1.05, 95%CI 1.01–1.09, P = 0.003). AAA-1 was not an independent FLI predictor. Conclusions: AAA-1 induce a NAFLD-compatible phenotype in vitro and in mice. Intricate associations exist between AAA-1, CVD risk and FLI in the general population. Further work is required to refine the role of AAA-1 in NAFLD and to determine if the AAA-1 association with CVD is affected by hepatic steatosis. [ABSTRACT FROM AUTHOR]

Background Deficiency of the essential trace element selenium is common in kidney transplant recipients (KTR), potentially hampering antioxidant and anti-inflammatory defence. Whether this impacts the long-term outcomes of KTR remains unknown. We investigated the association of urinary selenium excretion, a biomarker of selenium intake, with all-cause mortality; and its dietary determinants. Methods In this cohort study, outpatient KTR with a functioning graft for longer than 1 year were recruited (2008–11). Baseline 24-h urinary selenium excretion was measured by mass spectrometry. Diet was assessed by a 177-item food frequency questionnaire, and protein intake was calculated by the Maroni equation. Multivariable linear and Cox regression analyses were performed. Results In 693 KTR (43% men, 52 ± 12 years), baseline urinary selenium excretion was 18.8 (interquartile range 15.1–23.4) μg/24-h. During a median follow-up of 8 years, 229 (33%) KTR died. KTR in the first tertile of urinary selenium excretion, compared with those in the third, had over a 2-fold risk of all-cause mortality [hazard ratio 2.36 (95% confidence interval 1.70–3.28); P  < .001], independent of multiple potential confounders including time since transplantation and plasma albumin concentration. The most important dietary determinant of urinary selenium excretion was protein intake (Standardized β 0.49, P  < .001). Conclusions Relatively low selenium intake is associated with a higher risk of all-cause mortality in KTR. Dietary protein intake is its most important determinant. Further research is required to evaluate the potential benefit of accounting for selenium intake in the care of KTR, particularly among those with low protein intake. [ABSTRACT FROM AUTHOR]

Context: The phosphate-regulating hormone fibroblast growth factor 23 (FGF23) has been linked to deregulations in glucose metabolism, but its role is insufficiently understood. Objective: This study investigates potential crosstalk between FGF23 and glucose homeostasis. Methods: First, we investigated the effect of glucose loading on plasma C-terminal FGF23 levels and its temporal relationship with changes in plasma phosphate in 45 overweight (body mass index [BMI] 25-30) individuals using time-lag analyses. Second, we studied cross-sectional associations of plasma C-terminal FGF23 levels with glucose homeostasis using multivariable linear regression in a population-based cohort. We also investigated associations of FGF23 with incident diabetes and obesity (BMI > 30) in individuals without diabetes or obesity at baseline, respectively, using multivariable Cox regression analyses. Finally, we explored whether the association between FGF23 and diabetes depends on BMI. Results: After glucose loading, changes in FGF23 preceded changes in plasma phosphate (Ptime-lag = .04). In the population-based cohort (N = 5482; mean age 52 years, 52% women, median FGF23 69 RU/mL), FGF23 was associated with plasma glucose (β = .13 [.03-.23]; P = .01), insulin (β = .10 [.03-.17]; P < .001), and proinsulin (β = .06 [0.02-0.10]; P = .01) at baseline. On longitudinal analyses, a higher baseline FGF23 was independently associated with development of diabetes (199 events [4%]; fully adjusted hazard ratio [HR] 1.66 [95% CI, 1.06- 2.60]; P = .03) and development of obesity (241 events [6%]; fully adjusted HR 1.84 [95% CI, 1.34-2.50]; P < .001). The association between FGF23 and incident diabetes lost significance after additional adjustment for BMI. Conclusion: Glucose loading has phosphate-independent effects on FGF23 and, vice versa, FGF23 is associated with glucose, insulin and proinsulin levels, and obesity. These findings suggest crosstalk between FGF23 and glucose homeostasis, which may promote susceptibility to incident diabetes. [ABSTRACT FROM AUTHOR]

This article discusses the importance of accurately estimating glomerular filtration rate (GFR) in medical care and clinical decision-making. The current guidelines recommend using serum creatinine as the initial test and an estimating equation to calculate GFR. If the estimated GFR is considered less accurate, confirmatory testing with cystatin C is recommended. However, the performance of cystatin C as a GFR marker in real-world settings is not well-studied. A recent study found that using both creatinine and cystatin C for estimating GFR outperforms using either marker alone, particularly when there is discordance between the two markers. The study also highlights the impact of rounding levels of kidney function markers on the performance of GFR-estimating equations, emphasizing the need for accurate measurement and reporting of creatinine and cystatin C values. [Extracted from the article]

With rising incidence and prevalence of type 2 diabetes, prevention including identification of prospective biomarkers becomes increasingly relevant. Although ketone bodies recently received a renewed interest as potential biomarkers, data linking these metabolites to diabetes risk are scarce. Therefore, the present prospective study investigated a potential association between fasting ketone bodies and incident type 2 diabetes in the general population. This study from the PREVEND cohort included 3,307 participants from the general population initially free of diabetes or impaired fasting glucose. Baseline fasting ketone body concentrations were measured by nuclear magnetic resonance spectroscopy. One hundred twenty-six participants (3.8%) developed type 2 diabetes during a median (interquartile range) follow-up of 7.3 (6.3-7.6) years. In Kaplan-Meier analysis, sex-stratified ketone body levels strongly positively associated with incident type 2 diabetes, which was confirmed in Cox regression analyses adjusted for several potential confounders. There was no significant interaction by sex. Both 3-β-hydroxybutyrate and acetoacetate+acetone individually associated with incident type 2 diabetes. In conclusion, fasting plasma ketone body levels are strongly positively associated with incident type 2 diabetes in the general population independent of several other recognized risk factors. These results may have important implications for diabetes prevention including dietary strategies. [ABSTRACT FROM AUTHOR]

Background: The risk of chronic diseases increases markedly with age and after menopause. An increase in bodily iron following menopause could contribute to this phenomenon of increased risk of chronic diseases. We aimed to investigate how various iron biomarkers change with advancing age, according to sex and menopausal status. Methods: We enrolled community-dwelling individuals with available information on ferritin, transferrin, iron, hepcidin, and soluble transferrin receptor levels from the Prevention of Renal and Vascular Endstage Disease study. The association of the iron biomarkers with age, sex, and menopausal status was investigated with linear regression models. Results: Mean (SD) age of the 5222 individuals (2680 women [51.3%], among whom 907 [33.8%] were premenopausal, 529 [19.7%] perimenopausal, and 785 [29.3%] postmenopausal), was 53.4 (12.0) years. Iron biomarkers showed a constant increase in women throughout their life course, in some cases at older ages surpassing values in men who, in turn, showed consistently higher levels of iron status compared to women in most age categories. Ferritin, hepcidin, and transferrin saturation levels were 3.03, 2.92, and 1.08-fold (all p < 0.001) higher in postmenopausal women compared to premenopausal. Conclusions: We found that iron accumulates differently depending on sex, age, and menopausal status. An increased iron status was identified in women, especially during and after menopause. [ABSTRACT FROM AUTHOR]

Background Long-term high-dose lithium therapy in bipolar disorder is known to adversely affect kidney function. However, recent animal studies have revealed that low amounts of lithium are beneficial for the kidney when it is damaged by exposure to nephrotoxic compounds, inflammation or oxidative stress. This study aimed to investigate whether urinary lithium excretion, reflecting dietary lithium intake, is associated with adverse long-term kidney graft outcomes and patient survival. Methods Urinary lithium concentration was measured using inductively coupled plasma mass spectrometry in 642 stable kidney transplant recipients (KTRs). Graft failure was defined as the start of dialysis or retransplantation and kidney function decline was defined as a doubling of serum creatinine. Results The median urinary lithium excretion was 3.03 μmol/24 h [interquartile range (IQR) 2.31–4.01]. Urinary lithium excretion was associated with energy, plant protein and water intake. During a median follow-up of 5.3 years (IQR 4.5–6.0), 79 (12%) KTRs developed graft failure and 127 (20%) KTRs developed kidney function decline. Higher urinary lithium excretion was associated with a lower risk of graft failure {hazard ratio [HR] per doubling 0.54 [95% confidence interval (CI) 0.38–0.79]} and kidney function decline [HR per doubling 0.73 (95% CI 0.54–0.99)]. These associations remained independent of adjustment for potential confounders and in sensitivity analyses. There was a significant effect modification with the use of proliferation inhibitors (P  = .05) and baseline estimated glomerular filtration rate (eGFR; P  < .001), with higher urinary lithium excretion being more protective in KTRs not using proliferation inhibitors and in KTRs with lower baseline eGFR. Furthermore, higher urinary lithium excretion was associated with a reduced risk of all-cause mortality [HR 0.64 (95% CI 0.49–0.83); P  = .001]. Conclusion Dietary lithium intake may be a potentially modifiable, yet rather overlooked, risk factor for adverse long-term kidney graft outcomes and patient survival. Trial registration https://clinicaltrials.gov/ct2/show/NCT02811835 [ABSTRACT FROM AUTHOR]

Background and Objective: Historically, dosing of tacrolimus is guided by therapeutic drug monitoring (TDM) of the whole blood concentration, which is strongly influenced by haematocrit. The therapeutic and adverse effects are however expected to be driven by the unbound exposure, which could be better represented by measuring plasma concentrations. Objective: We aimed to establish plasma concentration ranges reflecting whole blood concentrations within currently used target ranges. Methods: Plasma and whole blood tacrolimus concentrations were determined in samples of transplant recipients included in the TransplantLines Biobank and Cohort Study. Targeted whole blood trough concentrations are 4–6 ng/mL and 7–10 ng/mL for kidney and lung transplant recipients, respectively. A population pharmacokinetic model was developed using non-linear mixed-effects modelling. Simulations were performed to infer plasma concentration ranges corresponding to whole blood target ranges. Results: Plasma (n = 1973) and whole blood (n = 1961) tacrolimus concentrations were determined in 1060 transplant recipients. A one-compartment model with fixed first-order absorption and estimated first-order elimination characterised observed plasma concentrations. Plasma was linked to whole blood using a saturable binding equation (maximum binding 35.7 ng/mL, 95% confidence interval (CI) 31.0–40.4 ng/mL; dissociation constant 0.24 ng/mL, 95% CI 0.19–0.29 ng/mL). Model simulations indicate that patients within the whole blood target range are expected to have plasma concentrations (95% prediction interval) of 0.06–0.26 ng/mL and 0.10–0.93 ng/mL for kidney and lung transplant recipients, respectively. Conclusion: Whole blood tacrolimus target ranges, currently used to guide TDM, were translated to plasma concentration ranges of 0.06–0.26 ng/mL and 0.10–0.93 ng/mL for kidney and lung transplant recipients, respectively. [ABSTRACT FROM AUTHOR]

Background Neurocognitive impairment is common in kidney transplant recipients (KTRs). Adequate brain functioning requires energy and neurotransmitter activity, for which iron is essential. We aimed to investigate iron deficiency (ID) as a potentially modifiable risk factor for cognitive impairment in KTRs. Methods We analyzed stable KTRs participating in the TransplantLines Biobank and Cohort study. Participants underwent neuropsychological tests for memory, mental speed, and attention and executive functioning. ID was defined as ferritin <100 µg/mL or 100–299 µg/mL with transferrin saturation (TSAT) ≤20%. Associations between iron status and norm scores of neurocognitive outcomes, corrected for age, sex and education, were assessed using multivariable linear regression analyses adjusted for potential confounders including hemoglobin. Results We included 166 KTRs [median (IQR) age 57 (45–65) years, 59% male, estimated glomerular filtration rate 51±18 mL/min/1.73 m2]. Time since transplantation was 5.8 (1.0–12.0) years. Prevalence of ID was 65%. ID was independently associated with lower scores for mental speed (std.β = –0.19, P  = .02) and attention and executive functioning (std.β = –0.19, P  = .02), and tended to be associated with worse memory (std.β = –0.16, P  = .07). Lower plasma ferritin levels were associated with worse memory (std.β = 0.23, P  = .007), mental speed (std.β = 0.34, P  < .001), and attention and executive functioning (std.β = 0.30, P  = .001). Lower TSAT was associated with worse memory (std.β = 0.19, P  = .04) and mental speed (std.β = 0.27, P  = .003), and tended to be associated with worse attention and executive functioning (std.β = 0.16, P  = .08). Conclusions Iron-deficient KTRs performed worse on neurocognitive tasks measuring memory, mental speed, and attention and executive functioning. These findings set the stage for prospective studies addressing whether ID correction restores cognitive function after kidney transplantation. [ABSTRACT FROM AUTHOR]

Alterations in apoptosis, as reflected by circulating Cytokeratin 18 (CK18), are involved in the progression of non-alcoholic fatty liver disease (NAFLD) to non-alcoholic steatohepatitis and atherogenesis. We aimed to explore the discriminant accuracy of Cytokeratin 18 (CK18, including M65 and M30 forms) for an elevated fatty liver index (FLI) as a validated proxy of NAFLD, and cardiovascular disease (CVD) risk in the general population. Both serum CK18 forms were measured using a commercial immunoassay in randomly selected samples from 312 participants of the PREVEND general population cohort. FLI ≥ 60 was used to indicate NAFLD. Framingham Risk Score (FRS) and the SCORE2 were used to estimate the 10-year risk of CVD. The Receiver Operating Characteristic (ROC) curve, linear/logistic regression models, and Spearman's correlations were used. Intricate associations were found between CK18, FLI, and CVD risk scores. While M30 was the only independent predictor of FLI ≥ 60, M65 best discriminated NAFLD individuals at very-high 10-year CVD risk according to SCORE2 (AUC: 0.71; p = 0.001). Values above the predefined manufacturer cutoff (400 U/L) were associated with an independent 5-fold increased risk (adjusted odds ratio: 5.44, p = 0.01), with a negative predictive value of 93%. Confirming that NAFLD is associated with an increased CVD risk, our results in a European general population-based cohort suggest that CK18 M65 may represent a candidate biomarker to identify NAFLD individuals at low CVD risk. [ABSTRACT FROM AUTHOR]

Objective: Fibroblast growth factor 21 (FGF21) is a peptide hormone synthesized by several organs and regulates, among others, energy homeostasis. In obesity, insulin resistance and type 2 diabetes (T2D), higher circulating FGF21 concentrations have been found. Temporal analyses in murine studies demonstrate that FGF21 increases before insulin resistance occurs. The current study aims to investigate in timeto- event analyses whether FGF21 may be an early biomarker in the development of T2D. Research Design and Methods: Circulating FGF21 was measured using an immunoassay of the Mesoscale U-PLEX assay platform. The study outcome was incident T2D. Associations of circulating FGF21 concentration with T2D were quantified using Cox proportional hazards models with adjustments for potential confounders. Results: We included 5244 participants aged 52± 12 years, of whom 50% were male. Median [interquartile range] circulating FGF21 concentration was 860 [525-1329] pg/mL. During 7.3 [6.1-7.7] years of follow-up, 299 (5.7%) participants developed T2D. In fully adjusted analyses, higher circulating FGF21 concentration was associated with an increased risk of incident T2D (hazard ratio per doubling: 1.26 [95% CI, 1.06-1.51]; P= 0.008), with effect modification by fasting plasma glucose, consistent with strengthening of the association at lower fasting glucose (interaction coefficient: -0.12; P= 0.022). Conclusion: Higher circulating FGF21 concentrations are independently associated with an increased risk of incident T2D in participants with a low fasting plasma glucose, making circulating FGF21 concentration a potential early biomarker for type 2 diabetes. [ABSTRACT FROM AUTHOR]

Purpose: GlycA, a pro-inflammatory glycoprotein biomarker, associates with newly developed type 2 diabetes (T2D). We determined the association of plasma GlycA with the development of microvascular complications in patients with established T2D. Methods: Plasma GlycA was measured by nuclear magnetic resonance spectrometry in T2D patients without microvascular complications at baseline (n = 145) participating in a longitudinal cohort study of primary care-treated T2D patients (Zwolle Outpatient Diabetes project Integrating Available Care (ZODIAC) study). Associations of GlycA with incident microvascular complications including nephropathy, retinopathy, and neuropathy, were determined by Cox proportional hazards regression analyses. Results: After a median follow-up of 3.2 (interquartile range [IQR]: 2.9–3.4) years, 49 patients (33.8%) developed one or more microvascular complications. Median GlycA levels were 453.5 (IQR: 402.0–512.8) μmol/l. GlycA was associated with incident microvascular complications (hazard ratio [HR] per 1-SD increment: 1.28 [95% confidence interval [CI]:1.00–1.63], P = 0.048]), even after adjustment for potential confounders and high-sensitive C-reactive protein (hs-CRP), HR 1.79 [95%CI:1.25–2.57], P = 0.001). In contrast, hs-CRP levels were not significantly associated with the risk of developing microvascular complications (P = 0.792). Conclusion: Higher plasma GlycA is associated with an increased risk of developing microvascular complications in T2D patients. Altered N-glycan branching associated with acute-phase reactive proteins may represent a preferred biomarker of systemic low-grade inflammation in predicting diabetic complications. [ABSTRACT FROM AUTHOR]

Decreased circulating branched chain amino acids (BCAA) represent a prominent change in amino acid profiles in patients with end-stage liver disease (ESLD). These alterations are considered to contribute to sarcopenia and hepatic encephalopathy and may relate to poor prognosis. Here, we cross-sectionally analyzed the association between plasma BCAA levels and the severity of ESLD and muscle function in participants of the liver transplant subgroup of TransplantLines, enrolled between January 2017 and January 2020. Plasma BCAA levels were measured by nuclear magnetic resonance spectroscopy. Physical performance was analyzed with a hand grip strength test, 4 m walking test, sit-to-stand test, timed up and go test, standing balance test and clinical frailty scale. We included 92 patients (65% men). The Child Pugh Turcotte classification was significantly higher in the lowest sex-stratified BCAA tertile compared to the highest tertile (p = 0.015). The times for the sit-to-stand (r = −0.352, p < 0.05) and timed up and go tests (r = −0.472, p < 0.01) were inversely correlated with total BCAA levels. In conclusion, lower circulating BCAA are associated with the severity of liver disease and impaired muscle function. This suggests that BCAA may represent a useful prognostic marker in the staging of liver disease severity. [ABSTRACT FROM AUTHOR]

Low muscle mass and myosteatosis are associated with poor clinical outcomes. Computed tomography (CT) imaging is an objective method for muscle mass and quality assessment; however consensus on cut-off values is lacking. This study assessed age-, sex-, and body mass index (BMI)-specific reference values of skeletal muscle parameters and correlated muscle mass with 24-h urinary creatinine excretion (24-h UCE). In total, 960 healthy subjects were included in this study. Muscle mass and quality were determined using axial CT slices at the vertebral level L3. The muscle area was indexed for height (skeletal muscle index [SMI]). The mean age was 53 ± 11 years, and 50% were male. The SMI reference values for low muscle mass in males were 38.8 cm2/m2 (20–29 years), 39.2 (30–39 years), 39.9 (40–49 years), 39.0 (50–59 years), 37.0 (60–69 years), and 36.8 (70–79 years). For females, these reference values were 37.5 cm2/m2 (20–29 years), 35.5 (30–39 years), 32.8 (40–49 years), 33.2 (50–59 years), 31.2 (60–69 years), and 31.5 (70–79 years). 24-h UCE and SMI were significantly correlated (r = 0.54, p < 0.001) without bias between the two methods of assessing muscle mass. This study provides age-, sex-, and BMI-specific reference values for skeletal muscle parameters that will support clinical decision making. [ABSTRACT FROM AUTHOR]

Background Fibrosis is a suggested cause of graft failure and mortality among kidney transplant recipients (KTRs). Accumulating evidence suggests that collagen type VI is tightly linked to fibrosis and may be a marker of systemic fibrosis and ageing. We studied whether plasma endotrophin, a pro-collagen type VI fragment, is associated with graft failure and mortality among KTRs. Methods In cohort A (57% male, age 53 ± 13 years), we measured plasma endotrophin in 690 prevalent KTRs ≥1 year after transplantation. The non-overlapping cohort B included 500 incident KTRs with serial endotrophin measurements before and after kidney transplantation to assess trajectories and intra-individual variation of endotrophin. Results In cohort A, endotrophin was higher in KTRs compared with healthy controls. Concentrations were positively associated with female sex, diabetes, cardiovascular disease, markers of inflammation and kidney injury. Importantly, endotrophin was associated with graft failure {hazard ratio [HR] per doubling 1.87 [95% confidence interval (CI) 1.07–3.28]} and mortality [HR per doubling 2.59 (95% CI 1.73–3.87)] independent of potential confounders. Data from cohort B showed that endotrophin concentrations strongly decrease after transplantation and remain stable during post-transplantation follow-up [intra-individual coefficient of variation 5.0% (95% CI 3.7–7.6)]. Conclusions Plasma endotrophin is strongly associated with graft failure and mortality among KTRs. These findings suggest a key role of abnormal extracellular matrix turnover and fibrosis in graft and patient prognosis among KTRs and highlight the need for (interventional) studies targeting the profibrotic state of KTRs. The intra-individual stability after transplantation indicates potential use of endotrophin as a biomarker and outcome measure of fibrosis. Trial registration ClinicalTrials.gov NCT02811835. [ABSTRACT FROM AUTHOR]