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Because dietary ingredients and feeding patterns influence the volume, pH and solute concentration of urine, diet can contribute to the etiology, management or prevention of recurrence of some causes of lower urinary tract disease. Most research assessing the effect of diet has focused on the latter two aspects, primarily because of interest in struvite urolithiasis. Manipulation of urine pH through dietary means has proven an effective tool for the management and prevention of struvite urolithiasis; acidification of urine, however, may be a risk factor for calcium oxalate urolithiasis, which now appears to occur with approximately equal frequency in cats. Prediction of urine pH from dietary analysis would thus be a valuable tool, but considerable further research is required before this can be achieved with commercial canned foods. With the growing importance of urolith types other than struvite, alternatives to the measurement of urine pH are required to assess critically the likely beneficial (or detrimental) effects of manipulation of nutrient profile. Measurement of urinary saturation may permit the development and fine tuning of nutrient profiles aimed at controlling lower urinary tract diseases in cats that are associated with a range of different mineral types. The majority of cats with signs of lower urinary tract disease do not, however, have urolithiasis; indeed, no specific cause can be established in most of these cats. Recent observations suggest that recurrence rates of signs in cats classified as having idiopathic lower urinary tract disease may be more than halved if affected animals are maintained on high, rather than low moisture content diets. J. Nutr. 2753S-2757S, 1998 [ABSTRACT FROM AUTHOR]

Aims The present study assessed the influence of urinary flow rate and urine pH on the renal excretion of the NMDA-receptor antagonist memantine. Methods In a randomized, open, four-period cross-over trial, 12 healthy male volunteers received 10 mg memantine daily for 43 days. After reaching steady state conditions the volunteers were allocated to four different regimens to alter urine pH and urinary flow, which were each separated by a 1 week period while the study medication continued (A: acidification of urine pH, low urinary flow; B: acidification of urine pH, high urinary flow; C: alkalinization of urine pH, low urinary flow; D: alkalinization of urine pH, high urinary flow). Results The renal clearance of memantine (CLR ) in regimen A and B was 7–10 fold higher in comparison with regimen C and D (P<0.05). There were small but statistically significant differences of CLR between the two regimens with acidic urine pH (A: median: 210.2 ml min-1 vs B: median: 218.7 ml min-1 ) and between the two regimens with alkaline urine pH (C: median: 19.4 ml min-1 vs D: median: 30.5 ml min-1 ). The amount of memantine excreted into the urine within one regimen (Ae0–24 h ) was 5.7–7.4 fold higher in regimens A and B than C and D (P<0.05). Differences of the AUC(0,24 h) and Cmax/AUC(0,24 h) were significant (P<0.05) between each of the regimens with acidic urine pH (A, B) and regimens (C, D) with alkaline urine pH (A vs C, A vs D, B vs C, B vs D) but not between regimens A vs B or C vs D. Conclusions The present study demonstrated a considerable effect of urine pH, whereas no clinically relevant change of the renal excretion of memantine with urinary flow could be detected. As the renal excretion of memantine may have an impact on therapeutic efficacy changes of dietary habits that may alter urine pH should be avoided during treatment with memantine. [ABSTRACT FROM AUTHOR]

It is reasonable to assume that the rate of pH increase in urine induced by urease-producing microorganisms is one of the factors which determine whether crystallisation with subsequent stone formation will occur or not. To evaluate how the time needed to increase urine pH varies between different urine samples and how it depends on urine composition, a standardised amount of urease was added to different human urine samples. The incubations were performed in a pH-stat. This allowed simultaneous study of how urease enzymatic activity depends on urine pH and how it varies between different urines. The enzymatic activity was found to be negatively correlated to urine pH and to vary between different urines. The rate of the pH increase varied markedly between different urines. Small pH increases depended on the native urine pH and urease enzymatic activity. Higher pH increases up to the levels of phosphate crystallisation depended more on urine phosphate, the major urine buffer. The results presented show that urine composition influences the urease-induced pH increase. This might have clinical implications. [ABSTRACT FROM AUTHOR]

To maintain acid-base balance, the kidney must generate new bicarbonate by metabolizing glutamine and excreting ammonium (NH). During chronic metabolic acidosis, the kidney should respond by increasing the rate of excretion of NH to 200-300 mmol/day. If the rate of excretion of NH is much lower, the kidney is responsible for causing or perpetuating the chronic metabolic acidosis. Thus, the first step in the assessment of hyperchloraemic metabolic acidosis is to evaluate the rate of excretion of NH. It is important to recognize that the urine pH may be misleading when initially assessing the cause of this acidosis, as it does not necessarily reflect the rate of excretion of NH. If proximal renal tubular acidosis (RTA) is excluded, low NH excretion disease may be broadly classified into problems of NH production and problems of NH transfer to the urine; the latter being due to either interstitial disease or disorders of hydrogen ion secretion. The measurement of the urine pH at this stage may identify which problem predominates. This approach returns the focus of the investigation of RTA from urine pH to urine NH. [ABSTRACT FROM AUTHOR]

Distal renal tubular acidosis (dRTA) is not a single disease. The experimental forms of the syndrome are unsatisfactory as models of the naturally occurring disease, not least because they are seldom complicated by nephrocalcinosis, which is present in the majority of patients with spontaneous disease and contributes to the renal tubular defects found in the syndrome. Impairment of minimal urine pH, reduced urine carbon dioxide tension ( PCO) during passage of alkaline urine, and reduced urinary ammonium (NH) excretion, have all been advocated as essential criteria for the diagnosis of dRTA. Minimal urine pH, measured during metabolic acidosis, sulphate infusion, or after oral frusemide, is the yardstick against which other criteria should be assessed. A reduced urinary PCO is commonly found in dRTA but is not specific for the syndrome and may be accounted for by tubular defects other than those involving reduced distal hydrogen ion secretion. NH excretion is reduced in most patients with renal acidosis whatever the nature of the underlying renal disease; this function is closely related to nephron mass, and is not specifically impaired in renal tubular disease. [ABSTRACT FROM AUTHOR]

The object of this study was to determine whether it is possible to reliably estimate the renal net acid excretion (NAE) produced by adults consuming different amounts of dietary protein. A physiologically based calculation model that corrects for intestinal absorption of minerals and sulfur-containing protein and assumes a rate of urinary excretion of organic acids proportional to body surface area was used to estimate NAE. Urinary excretion of different minerals and NAE was measured during the last 48 h of each of four separate 5-d diet periods in six healthy adults. On the basis of food tables, the four nearly isoenergetic diets (one lactovegetarian and one high- and two moderate-protein diets) were estimated to yield the following NAE values: 3.7, 117.5, 62.2, and 102.2 mEq/d, respectively. The analytically determined urinary NAE (24.1 ± 10.7, 135.5 ± 16.4, 69.7 ± 21.4, and 112.6 ± 10.9 mEq/d) corresponded reasonably well to these estimates, suggesting that the calculation model is appropriate to predict the renal NAE from nutrient intake and anthropometric data. [ABSTRACT FROM AUTHOR]

Hydration and urinary alkalinization are used with high doses of methotrexate (MTX) to prevent precipitation of the drug in the renal tubules and consequential nephrotoxicity. The quantitative effect of these measures on the renal clearance of MTX was studied in 8 patients with normal renal function, and in 3 patients with reduced renal function. Multiple regression analysis indicated an influence of both factors on the ratio of the renal clearances of MTX and creatinine. In the eleven patients there was a linear correlation between this ratio and urine pH ( p<0.001); the ratio increased from 0.88 at pH 5.5 to 2.62 at pH 8.4. The pH effect on this ratio was similar in the patients with normal and reduced kidney function. An increase in urine flow did not significantly increase the ratio between renal clearance of MTX and creatinine. The effect of urinary alkalinization on renal MTX clearance could be clinically exploited in patients with delayed elimination of MTX. The probable modifying effect of alkalinization of urine on the intentionally high plasma concentration after high dose MTX infusions should be further evaluated, particularly in patients with normal renal function. [ABSTRACT FROM AUTHOR]

The effects of liver enzyme induction and of urine pH on the pharmacokinetics of chlorpropamide have been studied. A single oral dose of chlorpropamide 250 mg was administered to 8 patients on antiepileptic drugs (phenytoin, carbamazepine) and to 8 healthy volunteers. The half-life of chlorpropamide was significantly shorter in the patients (34.4 h) than in the healthy volunteers (50.2 h), but the difference between the groups in the half-life of antipyrine was even more pronounced (5.1 vs 11.4 h). The clearance and volume of distribution of total chlorpropamide were significantly higher in the patients (2.99 ml·h·kg and 126 ml·kg) than in the healthy volunteers (1.60 ml·h·kg and 106 ml·kg). The unbound fraction of chlorpropamide in serum was also higher in the patients (5.7%) than in the healthy subjects (4.4%). Neither the volume of distribution nor the clearance of the free fraction of chlorpropamide differed significantly between the groups. There was a significant correlation between the half-lifes of chlorpropamide and antipyrine, and the half-life of chlorpropamide also had at least as good an inverse correlation with the urinary excretion of unchanged chlorpropamide. The renal clearance of chlorpropamide correlated well with urine pH and was almost 100-fold higher at pH 7 than at pH 5. Both the metabolic and renal clearances of chlorpropamide are important in its elimination. At urine pH higher than 6.5-7, the renal clearance of chlorpropamide represents more than half its total clearance regardless the degree of induction of liver enzymes. [ABSTRACT FROM AUTHOR]

The most common risk factors for cardiovascular disease and urolithiasis are presented in the article. Data on the prevalence of urolithiasis are discussed, as well as the pathogenetic mechanisms of stone formation in patients with metabolic syndrome, dyslipidemia, and arterial hypertension. The bi-directional relationship of cardiovascular risk factors and urolithiasis is generalized. The role of calcium, uric acid, citrate, changes in urine pH and an increase in body weight in the formation of kidney stones is shown.

Objectives: Portable pH meters are robust and reliable tools for measuring urinary pH bypatients at home. This study evaluated the usability of a prototype smart Lit-Control® pH Meter and an associated mobile medical app, with the aim of identifying possible design and functionality issues along with usability problems among non-expert voluntary users., Matherials and Methods: Twenty-one individuals of both genders, between 26 and 61 years old, tested the dyad pH meter/app for 14 days (three readings per day). The participants were asked to carry out a sequence of use of the system equivalent to what an intended user would do for urinary pH self-monitoring. At the end of the trial period, each participant filled out study questionnaires regarding the learning times, i.e. the time used by a new user to perform a task with the technology, usability, errors detected, and suggestions for improvement. RESULTS: The mean age of participants was 35.4 (range, 26 to 61) years. The readings from the pH meter yielded average values of 5.72 (SD = 0.26), 6.13 (SD= 0.43), and 5.47 (SD = 1.27) for the morning, evening, and night micturitions, respectively. The time of the day with greater adherence was the morning (49.7% of all readings). The learning times were in general short as reported by the participants: 73.7% were able to register in the App, rated as the least easy task, in less than two and a half minutes. The task of uploading the pH readings, both manually and automatically, was mostly performed in less than 35 seconds., Conclusion: This pilot study of real-world usage pattern shows that the dyad smart Lit-Control pH meter/Appwas perceived as fit for purpose by non-expert volunteers and had no relevant functionality or usability issues that would pose a significant barrier to the intended users. New studies are ongoing in order to test the usability by patients with lithiasis history.

Abstract: Objectives: To minimize toxicity of high-dose methotrexate (MTX) therapy, urinary alkalinization with frequent monitoring of urine pH is required. Urine pH is usually assessed by fast and convenient dipstick methods. When urine color interferes with dipstick measurement, as occurs in patients receiving MTX, alternative methods such as pH meters are used. Nursing staff caring for patients on high-dose MTX reported that urine pH results from dipstick and pH analyzers were often clinically discordant. As a result urine pH by dipstick and pH meter were compared in patients on high-dose MTX therapy and patients with normal-colored urine samples. Design and methods: We measured urine pH by dipstick and pH meter in 116 urine samples from 4 patients receiving high-dose MTX therapy, and in 50 normal-colored urine samples from 50 patients not on MTX therapy. Results: In patients on MTX therapy the mean (±standard deviation) bias between dipstick and pH meter urine pH was 0.7±0.4, compared to 0.4±0.3 in patients not on MTX. For patients on MTX clinical concordance between dipstick and pH meter urine results was poor around a clinical cut-off of pH8.0. Of the 92 samples with a meter urine pH≤8.0, 72 had a discordant value by dipstick (pH>8). Conclusions: Urine pH readings by dipstick and pH meter are not equivalent, and the bias between them is exacerbated in patients on MTX. Institutions with high-dose MTX therapy protocols should not alternate between dipstick and pH meter urine pH monitoring. [Copyright &y& Elsevier]

STUDY DESIGN::Pilot study; prospective design. SETTING::University Hospital, Virginia, USA. OBJECTIVE::To examine a phosphorus supplement as a urine-acidifying agent in patients with neurogenic bladder on clean intermittent catheterization. METHODS::Seven patients were followed for 4 weeks. For the first week of study urine pH was measured three times a day: first morning urine sample, afternoon sample, evening sample. For the second and third weeks urine pH was measured and the patients drank a phosphorus supplement three times a day. For the fourth week of study the patients did not take the phosphorus supplement but the measurement of urine pH was continued. The patients were visited in their homes twice a week. During each visit a sample of urine was collected for culture. A supplement container count was performed and urine pH recordings were checked. RESULTS::There was no significant change in urine pH during the 2-week period when a patient was on phosphorus supplementation compared to when the patient was off supplementation. In addition, urine acidification was not achieved over the time period when urine pH was monitored. CONCLUSION::Phosphate supplementation had no effect on urine pH in patients with neurogenic bladder.Spinal Cord (2005) 43, 187-189. doi:10.1038/sj.sc.3101700 Published online 30 November 2004 [ABSTRACT FROM AUTHOR]

Collection of urine under paraffin is routinely used in clinical practice for urine pH evaluation. To examine whether the accuracy of pH measurement is adversely influenced by the method of collection and storage, we divided each urine specimen and sent one aliquot to the laboratory under paraffin and another in a sealed 5-ml plastic syringe. In another experiment we evaluated the stability of urine pH measurement in a clinical setting. Urine collected under paraffin was tested immediately for pH; an aliquot from the same specimen was stored in a capped 5-ml syringe at 4°C and tested after 24 h. We found no appreciable difference in measured pH between samples sent to the laboratory under paraffin or in a capped plastic syringe. [ABSTRACT FROM AUTHOR]

Aim: Study findings examining the association between dietary acid load (DAL), kidney function and risk of chronic kidney disease (CKD) are inconsistent and there has been no meta-analysis on the relationship between DAL, kidney function and risk of CKD, hence we investigated this association in this paper. Methods: PubMed, ISI web of science and Scopus were searched up to January 2018 to identify all relevant articles. Effect sizes of eligible studies were pooled in random- effect model using the Der Simonian-Laird method. The I 2 Twenty three studies with 200092 subjects were included. Meta-analysis of 9 observational studies showed that DAL had a positive significant association with risk of CKD (1.31; 95% CI: 1.06, 1.62; P = 0.011). Furthermore, increased DAL can decrease urine pH (-0.47; 95% CI: -0.85, -0.08; P = 0.017) significantly. Subgroup analysis could not identify the sources of heterogeneity about the association of DAL and risk of CKD. However, it showed the method of measurement was the source of heterogeneity about the association of DAL and urine pH (24 h urine pH: -0.62; 95% CI: -0.70, -0.54; P < 0.0001; Fasting urine pH: -0.08; 95% CI: -0.18, 0.02; P = 0.111). Result: Our study showed that DAL can increase the risk of CKD and have an inverse association with urine pH.Conclusion: Our study showed that DAL can increase the risk of CKD and have an inverse association with urine pH.

Background/purpose: Urinary tract infections (UTIs) are one of the most common pediatric infections. Our objective in this study is to investigate the association between urine pH and uropathogens in pediatric patients., Methods: The source population comprised 26 066 paired urinalysis (UA) and urine culture (UC) samples obtained from pediatric patients. We classified the paired UA-UC samples into UTI positive (N = 6348) and UTI negative (N = 19 718) according to the colony forming units corresponding to the sampling source. We included UTI positive patients with infection caused by a single species of pathogen (N = 5201) and frequency matched them with UTI negative patients (N = 4729) by age, sex, sampling source, and visit type., Results: This study included 5201 pediatric patients with UTIs and found that urine with Proteus mirabilis or Pseudomonas aeruginosa demonstrated the least acidic pH (mean pH = 6.72 and 6.62, respectively), whereas urine with Escherichia coli or Klebsiella pneumoniae exhibited the most acidic pH (pH = 6.21 and 6.18). After stratifying the UTI samples by their pH range (<6, 6-6.9, 7-7.9, and ≥8). The prevalence of P. mirabilis increased significantly across increasing pH categories., Conclusion: This research is the first epidemiological study that linked urine pH to specific uropathogens in a pediatric population. Both urine pH and age are associated with certain causative uropathogens. Urine that grew P. mirabilis or P. aeruginosa had the least acidic pH. Additional studies should validate the role of urine pH in predicting uropathogens and UTI., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflicts of interest relevant to the manuscript that is being submitted to the Journal of Microbiology, Immunology and Infection., (Copyright © 2019. Published by Elsevier B.V.)

Objectives: The function of the N-methyl-D-aspartate receptor (NMDAR) in the kidney has been studied. However, the effect on the kidney from anti-NAMDAR antibody encephalitis has not been investigated thus far. Methods: Case data were collected from 82 patients with anti-NMDAR antibody encephalitis and 166 age- and sex-matched healthy controls (HCs). Clinical characteristics, urinalysis [including urine pH and urine specific gravity (SG)], serum creatinine (Scr), and estimated glomerular filtration rate (eGFR) based on Cr levels were evaluated. Results: At initial admission, urine pH levels and urine SG levels in anti-NMDAR antibody encephalitis patients were significantly higher and lower, respectively, than HCs (both p < 0.001). There were no significant differences in Scr and eGFR between anti-NMDAR antibody encephalitis patients and HCs. Urine pH levels in patients with anti-NMDAR antibody <1:32 were significantly lower than those in patients with anti-NMDAR antibody ≥1:32 ( p = 0.029). Urine pH levels were significantly lower ( p = 0.004) and urine SG levels were significantly higher ( p = 0.027) in a follow-up evaluation 3 months after treatment. Conclusions: The changes in urinalysis occur in patients with anti-NMDAR antibody encephalitis. The pathophysiological changes in anti-NMDAR antibody encephalitis were not limited to the CNS., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Liu, Gu, Liu, Liu, Xu, Fan, Peng and Jiang.)

Aims/introduction: A low level of urine pH (U-pH) has been reported to be associated with metabolic disorders. However, the relationship between the incidence of diabetes mellitus and U-pH has not yet been fully addressed., Materials and Methods: We investigated the relationship between U-pH and the development of diabetes mellitus during a 10-year period in a general population of individuals who received annual health examinations in 2006 (n = 28,990). After exclusion of individuals with missing data, and those with diabetes mellitus and/or chronic kidney disease at baseline, a total of 12,476 individuals (men/women: 8,027/4,449) who received health examinations at least once during the period from 2007 to 2016 were recruited. The recruited individuals were divided into four groups according to their U-pH levels: groups of U-pH ≤5.0, 5.5, 6.0 and ≥6.5., Results: During a 10-year period, 521 men (6.5%) and 132 women (3.0%) had new onset of diabetes mellitus. The cumulative incidence of diabetes mellitus was 7.5% (men/women: 9.3%/4.4%) per 100 person-years. The hazard ratios (HRs) in the U-pH ≤5.0 (HR 1.93) and U-pH 5.5 groups (HR 1.46) were significantly higher than that in the U-pH ≥6.5 group as a reference for men, but not for women. After adjustment of age, obesity, fasting glucose, smoking and alcohol drinking habits, family history of diabetes mellitus, and use of drugs for hypertension and dyslipidemia, HR in the U-pH ≤5.0 group (HR 1.39) was significantly higher than that in the U-pH ≥6.5 group for men, but not for women., Conclusions: Low U-pH predicts new onset of diabetes mellitus in a general population of men., (© 2020 The Authors. Journal of Diabetes Investigation published by Asian Association for the Study of Diabetes (AASD) and John Wiley & Sons Australia, Ltd.)

Background/aim: Neutralization of the acidic tumor microenvironment, which is associated with both progression and drug resistance of cancer cells, may be a new treatment option for progressing forms of cancer. We conducted a case-control study to investigate the effects of alkalization therapy, consisting of an alkaline diet with supplementary oral sodium bicarbonate, in patients with metastatic or recurrent pancreatic cancer (study registration no.: UMIN000036126)., Patients and Methods: Thirty-six patients in the alkalization group (Karasuma Wada Clinic; alkalization therapy plus chemotherapy) were retrospectively compared to 89 patients in the control group (Kyoto University Hospital; chemotherapy only)., Results: The median overall survival (OS) in the alkalization group was significantly longer than that in the control group (15.4 vs. 10.8 months; p<0.005). In the alkalization group, mean urine pH was significantly increased after alkalization therapy [6.38±0.85 (before) vs. 6.80±0.71 (after); p<0.05]. Furthermore, the median OS of patients with increased urine pH (pH>7.0 or ΔpH>1.0) in the alkalization group was significantly longer than that of the control group., Conclusion: Alkalization therapy may enhance the effects of chemotherapy in patients with advanced pancreatic cancer., (Copyright© 2020, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Incidence of subclinical hypocalcemia in early postpartum dairy cows continues to be an animal welfare concern and an economic burden for producers. Feeding prepartum negative dietary cation-anion difference (DCAD) diets produces metabolic acidosis, which supports mobilization of bone calcium and reduces the incidence of hypocalcemia. Achieving a sufficient degree of metabolic acidosis without reducing dry matter intake (DMI) can be difficult. This study compared the ability of MegAnion (MA; Origination O2D Inc., Maplewood, MN), a new DCAD supplement designed to be more palatable than typical anionic salt sources, and another palatable commercial DCAD product, SoyChlor (SC; Landus Cooperative, Ralston, IA), to reduce urine pH (a surrogate for metabolic acidosis) without reducing prepartum DMI. A secondary objective was to assess the effect of these anionic supplements on postpartum serum calcium concentrations and DMI. Prepartum multiparous Holstein (HO) and crossbred (XX) cows were blocked by breed and expected calving date and randomly assigned within breed to total mixed rations (TMR) with MA or SC and DCAD values of -215 mEq/kg of DM. Cows (n = 56; 15 MA-HO, 12 SC-HO, 15 MA-XX, 14 SC-XX) consumed the treatment TMR for at least 19 d and completed the 28 d in milk (DIM) phase of the study. Urine and blood samples were collected weekly and at 1, 2, and 3 DIM. Data were analyzed as a randomized block design by repeated measures with week or DIM as the repeated effect. Prepartum urine pH decreased from 8.15 ± 0.27 before treatment to 6.12 ± 0.14 during treatment, was not affected by anionic supplement, and increased immediately after calving when all cows consumed the same early-lactation TMR. Prepartum serum calcium concentrations were not affected (2.34 vs. 2.33 ± 0.02 mmol/L) by treatment, whereas nonesterified fatty acids were lower (86 vs. 120 ± 10 mmol/L) and insulin was greater (215 vs. 174 ± 10 pmol/L) in cows fed MA than in cows fed SC. These differences are supported by the numerically greater prepartum DMI (1.2 kg/d) and energy balance (1.8 Mcal/d) of cows fed MA. However, pre- and postpartum DMI and other production variables, including body weight, body condition score, milk yield, and energy balance, were not affected by treatment. This lack of difference indicates that MA provides another effective source of anionic salts for diets designed to reduce urine pH and induce metabolic acidosis in prepartum dairy cows., (Copyright © 2020 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Low urine pH is a metabolic risk factor for stone formation. While medical therapy is typically prescribed (as urinary alkalinization), patients typically prefer dietary modifications. We aimed to assess capacity to alter urine pH with dietary management alone. We analyzed a retrospective cohort of stone formers seen between 2000 and 2015 with multiple 24-h urine collections (24hUC). Patients ≥ 18 years old with low urine pH (< 6.0) were included; those prescribed alkalinizing agents or thiazides were excluded. Demographic data, 24hUC parameters, and medications were abstracted. 24hUC was utilized to calculate gastrointestinal alkali absorption (GIAA). The primary outcome was urine pH ≥ 6.0 on second 24hUC. Predictors were selected utilizing multivariable logistic regression. The database consisted of 2197 stone formers; 224 of these met inclusion criteria. On second 24hUC, 124 (55.4%) achieved a favorable pH ≥ 6.0. On univariable analysis, a second pH ≥ 6.0 was associated with high initial pH, low initial sulfate, younger age, increase in citrate/GIAA/urine volume, and decrease in ammonium (P < 0.02). On multivariable analysis, high initial pH (OR = 23.64, P < 0.001), high initial GIAA (OR = 1.03, P = 0.001), lower initial sulfate (OR = 0.95, P < 0.001), increase in urine volume (OR = 2.19, P = 0.001), increase in GIAA (OR = 8.6, P < 0.001), increase in citrate (OR = 2.7, P = 0.014), decrease in ammonium (OR = 0.18, P < 0.001), and younger age (OR = 0.97, P = 0.025) were associated with a second pH ≥ 6.0. The analysis demonstrated a corrected AUC of 0.853. These data suggest that certain dietary recommendations (increases in urine volume, citrate, GIAA, and decreased acid load) may normalize urine pH in a select group of patients. This may allow urologists to counsel patients with low urine pH on possibility of success with dietary modification alone.

Background and Purpose: Increasing evidence has demonstrated that aquaporin-4 (AQP4) immunoglobulin G causes damage to the kidney in neuromyelitis optica spectrum disorder (NMOSD). However, changes in urinalysis in NMOSD have not been investigated thus far. Our objective was to evaluate the changes in urinalysis in NMOSD patients., Methods: Case data were collected from 44 patients with AQP4 antibody-positive NMOSD, 53 patients with multiple sclerosis (MS) and 79 age- and sex-matched healthy controls. Analyses of early morning urine and 24-h urine samples comparing NMOSD with MS patients were conducted., Results: In the acute phase, urine pH levels (P < 0.001) and urine specific gravity levels (P < 0.001) from NMOSD patients were significantly higher and lower, respectively, than for MS patients. 24-h urine sodium and 24-h urine volume from NMOSD patients were significantly higher than for MS patients (both P = 0.001). A 24-h urine volume higher than 2500 ml (odds ratio 11.7, 95% confidence interval 1.863-73.066) and a 24-h urine sodium higher than 200 mmol (odds ratio 16.0, 95% confidence interval 2.122-120.648) are more likely to occur in NMOSD patients in the acute phase than in MS patients., Conclusions: The urinalysis results were significantly different between NMOSD patients and MS patients. The pathophysiological changes in AQP4 antibody-positive NMOSD patients were not limited to the central nervous system., (© 2019 European Academy of Neurology.)

Background/aim: The acidic tumor microenvironment is associated both with the progression and drug resistance of cancer. We aimed to investigate the effects of alkalization therapy performed concurrently with chemotherapy on the survival of advanced pancreatic cancer patients (study registration: UMIN 000035659)., Patients and Methods: Twenty-eight patients with metastatic or recurrent pancreatic cancer were assessed in this study. Alkalization therapy consisted of an alkaline diet with supplementary oral sodium bicarbonate (3.0-5.0 g/day)., Results: The mean urine pH was significantly higher after the alkalization therapy (6.85±0.74 vs. 6.39±0.92; p<0.05). The median overall survival from the start of alkalization therapy of the patients with high urine pH (>7.0) was significantly longer than those with low urine pH (≤ 7.0) (16.1 vs. 4.7 months; p<0.05)., Conclusion: An alkalization therapy may be associated with better outcomes in advanced pancreatic cancer patients treated with chemotherapy., (Copyright© 2020, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

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Background Urinary tract infections (UTIs) are one of the most common indications for antibiotics in both the inpatient and outpatient setting. The purpose of this study was to examine the impact of urinary pH on recurrence of UTIs. A recent review article stated imaging should be considered for patients with a urinary pH of 7 or higher. This study examines the impact of pH on outcomes of patients with UTI to determine whether pH plays a role in recurrent infection and representations to the healthcare facility. Methods This was a retrospective chart review via the computerized patient record system. Patients over the age of 18 years who presented to the healthcare facility between January 1, 2005 to January 1, 2019 for treatment of UTIs were included in this study. Alkaline urine was defined as a urinary pH greater than or equal to 7, while acidic urine was defined as a urinary pH less than 7. Urease splitting organisms included Proteus spp. Providencia spp. and Morganella spp. Outcomes included recurrence and re-presentation to the healthcare facility within 30 days. Results A total of 793 patients were included in this study, of which 21.3% had alkaline urine. Patients with alkaline urine were more likely to have recurrence of UTI (8.3% vs. 4.3%). Patients with a catheter were more likely to have alkaline urine (30% vs 18%; P = 0.0005). As expected, alkaline urine was associated with a higher frequency of urease splitting organisms (19% in alkaline urine vs. 3% in acidic urine). Renal calculi were found in 3.6% of patients with alkaline urine; however, only 34.3% of patients with alkaline urine had imaging completed. The use of drugs which can alkalinize the urine did not differ significantly between groups. Conclusion Patients with an alkaline urinary pH were more likely to experience recurrence and readmission within 30 days. Imaging was performed in a minority of patients which may represent a potential target for stewardship programs. Alkaline urine may be a marker for urease splitting organisms and calculi formation. More widespread imaging may be able to detect stones, allowing for potential urologic intervention, preventing subsequent antibiotic courses and repeated healthcare presentations. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

Rationale & Objective: Higher urine net acid excretion (NAE) is associated with slower chronic kidney disease progression, particularly in patients with diabetes mellitus. To better understand potential mechanisms and assess modifiable components, we explored independent predictors of NAE in the CRIC (Chronic Renal Insufficiency Cohort) Study., Study Design: Cross-sectional., Setting & Participants: A randomly selected subcohort of adults with chronic kidney disease enrolled in the CRIC Study with NAE measurements., Predictors: A comprehensive set of variables across prespecified domains including demographics, comorbid conditions, medications, laboratory values, diet, physical activity, and body composition., Outcome: 24-hour urine NAE., Analytical Approach: NAE was defined as the sum of urine ammonium and calculated titratable acidity in a subset of CRIC participants. 22 individuals were excluded for urine pH < 4 (n = 1) or ≥7.4 (n = 19) or extreme outliers of NAE values (n = 2). From an analytic sample of 978, we identified the association of individual variables with NAE in the selected domains using linear regression. We estimated the percent variance explained by each domain using the adjusted R 2 from a domain-specific model., Results: Mean NAE was 33.2 ± 17.4 (SD) mEq/d. Multiple variables were associated with NAE in models adjusted for age, sex, estimated glomerular filtration rate (eGFR), race/ethnicity, and body surface area, including insulin resistance, dietary potential renal acid load, and a variety of metabolically active medications (eg, metformin, allopurinol, and nonstatin lipid agents). Body size, as indicated by body surface area, body mass index, or fat-free mass; race/ethnicity; and eGFR also were independently associated with NAE. By domains, more variance was explained by demographics, body composition, and laboratory values, which included eGFR and serum bicarbonate level., Limitations: Cross-sectional; use of stored biological samples., Conclusions: NAE relates to several clinical domains including body composition, kidney function, and diet, but also to metabolic factors such as insulin resistance and the use of metabolically active medications., (Published by Elsevier Inc.)

One of the main functions of the kidney is to excrete an acid load derived from both dietary and endogenous sources, thus maintaining the pH of other fluids in the body. Urine pH is also of particular interest in stone formers, since it determines the presence of either calcium phosphate or uric acid content in stones. Others have noted in epidemiological studies a rise in incidence of low pH-dependent uric acid stones with age, coinciding with a decrease in the incidence of high pH-dependent phosphate stones. Taken together, these trends are suggestive of a longitudinal decline in urine pH in stone-forming patients, and, if true, this could explain the observed trends in stone incidence. We studied 7,891 stone formers, all of whom collected a 24-h urine sample and matching serum. Multivariate modeling revealed that urine pH did indeed fall with age and particularly between the ages of 20 and 50 yr old in both men and women. We sought to explain this trend through the inclusion of traditionally understood determinants of urine pH such as urinary buffers, estimates of glomerular filtration, and dietary acid load, but these, taken together, accounted for but a small fraction of the pH fall. Gastrointestinal anion absorption was the strongest predictor of urine pH in all age groups, as we have previously reported in middle-aged normal men and women. However, we found that, despite a decreasing urine pH, gastrointestinal anion absorption increased monotonically with age. In fact, after adjustment for gastrointestinal anion absorption, urine pH declined more markedly, suggesting that bicarbonate-producing anion absorption is regulated in a manner that offsets the decline of urine pH.

Special high-K diets have cardioprotective effects and are often warranted in conjunction with diuretics such as furosemide for treating hypertension. However, it is not understood how a high-K diet (HK) influences the actions of diuretics on renal K + handling. Furosemide acidifies the urine by increasing acid secretion via the Na + -H + exchanger 3 (NHE3) in TAL and vacuolar H + -ATPase (V-ATPase) in the distal nephron. We previously found that an alkaline urine is required for large conductance Ca 2+ -activated K + (BK)-αβ4-mediated K + secretion in mice on HK. We therefore hypothesized that furosemide could reduce BK-αβ4-mediated K + secretion by acidifying the urine. Treating with furosemide (drinking water) for 11 days led to decreased urine pH in both wild-type (WT) and BK-β4-knockout mice (BK-β4-KO) with increased V-ATPase expression and elevated plasma aldosterone levels. However, furosemide decreased renal K + clearance and elevated plasma [K + ] in WT but not BK-β4-KO. Western blotting and immunofluorescence staining showed that furosemide treatment decreased cortical expression of BK-β4 and reduced apical localization of BK-α in connecting tubules. Addition of the carbonic anhydrase inhibitor, acetazolamide, to furosemide water restored urine pH along with renal K + clearance and plasma [K + ] to control levels. Acetazolamide plus furosemide also restored the cortical expression of BK-β4 and BK-α in connecting tubules. These results indicate that in mice adapted to HK, furosemide reduces BK-αβ4-mediated K + secretion by acidifying the urine.

AIMS To assess the effect of the administration of two oral Ca boluses on concentrations of total Ca, β-hydoxybutyrate (BHB) and non-esterified fatty acids (NEFA) in serum, and urine pH, in recently calved pasture-fed dairy cows. METHODS Friesian or Friesian cross Jersey cows from one dairy farm were blocked by age and randomly assigned to no treatment (control; n=14), or treatment (n=13) with two oral Ca boluses administered approximately 12 hours apart, with the first bolus being given within 14 hours of calving. Each bolus weighed 198 g and contained 43 g of Ca; 31 g of Ca from calcium chloride and 12 g of Ca from calcium sulfate. Cows were enrolled over three calendar days, and all cows were managed in one group during the 24-hour study period. Blood samples were collected at 0, 1, 2, 4, 8, 12, 13, 14, 16, 20 and 24 hours after the initial treatment. Serum from each time point was analysed for concentrations of total Ca, and from 0, 12, and 24 hours for NEFA and BHB. Urine was collected at 0, 12 and 24 hours for pH measurement and pH was categorised as <7 or ≥7. The effect of treatment on percentage change in concentrations of Ca in serum relative to 0 hours, and concentrations of NEFA, BHB and urine pH, was examined using multivariable repeated measures mixed models with cow as a random effect. RESULTS In the final multivariable model for percentage change in concentrations of Ca, there was an interaction between time and treatment (p=0.004), with the percentage increase being higher in treatment than control cows at 1, 2, 4, 8 and 13 hours. At 12 hours, 5/13 (41%) treated cows had a urine pH <7compared to 0/12 (0%) control cows (p<0.001), and at 24 hours 13/13 (100%) treated cows had urine pH <7 compared to 0/12 (0%) control cows (p<0.001). Over the 24-hour period, mean concentrations of NEFA or BHB in serum were similar in treated and control cows (p>0.3). CONCLUSIONS AND CLINICAL RELEVANCE Oral treatment with two Ca boluses increased concentrations of total Ca in serum and decreased urine pH in pasture-fed cows. This bolus has the potential to reduce the prevalence and duration of subclinical hypocalcaemia in recently calved cows.

Objective: We planned to examine the connection between serum uric acid (UA) values and prostatic calculi (PCal) presence and to evaluate the relation between PCal and other etiological factors., Methods: Patients between 20 and 60 years of age who were referred to the clinic with any reason and had non-contrast abdominal tomography (NCACT) for PCal were included in the study. While the patients were separated into 2 groups based on their serum UA level as ≥7 mg/dL (Group 1) and < 7 mg/dL (Group 2), NCACT was also divided into 2 groups as PCal presence (PCal+) and lack (PCal-) serum UA, calcium, phosphorus, sodium, prostate-specific antigen levels and urinary analysis results of the patients were evaluated and compared., Results: PCal were detected in 38 of 169 patients (22%). PCal presence was detected to be significantly high in Group 1 (p = 0.015). While Type A localization PCal were present both in Groups 1 and 2. Based on PCal presence, UA level was detected to be significantly high in PCal+ patients (p = 0.01). No significant difference was detected among the groups in biochemical parameters and urine-related parameters other than UA., Conclusion: A significant relation was found between high UA value and PCal in this study. These results may show that UA plays an active role in PCal etiology., (© 2018 S. Karger AG, Basel.)