Association of acidic urine pH with impaired renal function in primary gout patients: a Chinese population-based cross-sectional study

Abstract

Background Patients with gout frequently have low urinary pH, which is associated with the nephrolithiasis. However, the specific distribution of urinary pH and potential relationship of acidic urine pH to broader manifestations of kidney disease in gout are still poorly understood. Methods A 2016–2020 population-based cross-sectional study was conducted among 3565 gout patients in the dedicated gout clinic of the Affiliated Hospital of Qingdao University to investigate the association between low urinary pH and kidney disease. We studied patients that we defined to have “primary gout”, based on the absence of > stage 2 CKD. All subjects underwent 14 days of medication washout and 3-day standardized metabolic diet. We obtained general medical information, blood and urine biochemistries, and renal ultrasound examination on the day of the visit. The primary readouts were urine pH, eGFR, nephrolithiasis, renal cysts, microhematuria, and proteinuria. Patients were assigned into 5 subgroups (urine pH ≤5.0, 5.0 <pH≤ 5.5, 5.5 <pH< 6.2, 6.2 ≤pH≤ 6.9, and pH >6.9), aligning with the clinical significance of urine pH. Results Overall, the median urine pH and eGFR of all patients was 5.63 (IQR 5.37~6.09), and 98.32 (IQR 86.03~110.6), with acidic urine in 46.5% of patients. The prevalence of nephrolithiasis, microhematuria, and proteinuria were 16.9%, 49.5%, and 6.9%, respectively. By univariate analysis, eGFR was significantly associated with age, sex, duration of gout, tophus, body mass index, systolic blood pressure, diastolic blood pressure, fasting blood glucose, total cholesterol, serum utare, hypertension, diabetes, and urine pH. On multivariable analysis, eGFR was associated with age, sex, diastolic blood pressure, serum uric acid, hypertension, diabetes, and urine pH. Acidic urine pH, especially urine pH < 5.0, was significantly associated with the prevalence of kidney disease, including > stage 1 CKD, nephrolithiasis, kidney cyst, and microhematuria. Patients with 6.2 ≤ urine pH ≤ 6.9 and SU ≤ 480 μmol/L had the highest eGFR with the lowest prevalence of nephrolithiasis, microhematuria, and proteinuria. Conclusions Approximately half of gout subjects had acidic urine pH. Urine pH < 5.0 was associated with significantly increased nephrolithiasis, renal cyst, microhematuria, and proteinuria. The results support prospective clinical investigation of urinary alkalinization in selected gout patients with acidic urine pH.

Evaluation of Renal Function and Urinalysis in Children With Simple Febrile Convulsions

“…31 Acidic urine pH, particularly urine pH < 5.0, is significantly linked to renal injury. 32 Dehydration can also lead to an acidic urine pH. In this study, a substantial proportion of patients (46%) had a reduced urine pH, which could be attributed to their decreased kidney function and dehydration caused by fever.…”

Impact assessment of metabolite instability in the development and validation of LC–MS/MS bioanalytical assays for measurement of rosuvastatin in human plasma and urine samples

“…gout or bacterial infection), time of the day (e.g. immediately after a meal) or gender (Clarkson, 2011; He et al, 2022; Landry & Bazari, 2012; Rose et al, 2015; Welch et al, 2008; Worcester et al, 2018). We set out to test matrix benchtop stability in a manner similar to the plasma assay by testing three main factors: (1) the parent‐to‐metabolite ratio; (2) the pH; and (3) the temperature.…”

COVID‐19 Vaccination and Gout Flare Risk in Patients With Infrequent or Frequent Flares: A Prospective Cohort Study

“…Exclusion criteria include having any other vaccinations in the 3 months before the study; comorbid rheumatologic illnesses or other inflammatory conditions, such as rheumatoid arthritis or calcium pyrophosphate deposition disease; a gout flare in the past month before enrollment; or comorbidities that were contraindications for COVID‐19 vaccination. Considering that the proportion of female gout patients in the gout clinic of our hospital is less than 4%, only male gout patients were recruited in this study 17 …”

“…Considering that the proportion of female gout patients in the gout clinic of our hospital is less than 4%, only male gout patients were recruited in this study. 17 The available vaccines were inactivated virus vaccine (Sinovac Life) or recombinant adenovirus type-5-vectored vaccine (Sinopharm BIBP); both were two-dose vaccines at a 21-day interval. All participants voluntarily decided whether to receive the COVID-19 vaccination.…”