Oral alkalinizing supplementation suppressed intrarenal reactive oxidative stress in mild-stage chronic kidney disease: a randomized cohort study.

BACKGROUND: The beneficial effects of oral supplements with alkalinizing agents in patients with chronic kidney disease (CKD) have been limited to the severe stages. We investigated whether two types of supplements, sodium bicarbonate (SB) and potassium citrate/sodium citrate (PCSC), could maintain renal function in patients with mild-stage CKD. METHODS: This was a single-center, open-labeled, randomized cohort trial. Study participants with CKD stages G2, G3a, and G3b were enrolled between March 2013 and January 2019 and randomly assigned by stratification according to age, sex, estimated glomerular filtration rate (eGFR), and diabetes. They were followed up for 6 months (short-term study) for the primary endpoints and extended to 2 years (long-term study) for the secondary endpoints. Supplementary doses were adjusted to achieve an early morning urinary pH of 6.8-7.2. We observed renal dysfunction or new-onset cerebrovascular disease and evaluated urinary surrogate markers for renal injury. RESULTS: Overall, 101 participants were registered and allocated to three groups: standard (n = 32), SB (n = 34), and PCSC (n = 35). Two patients in the standard group attained the primary endpoints (renal stones and overt proteinuria) but were not statistically significant. There was one patient in the standard reduced eGFR during the long-term study (p = 0.042 by ANOVA). SB increased proteinuria (p = 0.0139, baseline vs. 6 months), whereas PCSC significantly reduced proteinuria (p = 0.0061, baseline vs. 1 year, or p = 0.0186, vs. 2 years) and urinary excretion of 8-hydroxy-2'-deoxyguanosine (p = 0.0481, baseline vs. 6 months). CONCLUSION: This study is the first to report supplementation of PCSC reduced intrarenal oxidative stress in patients with mild-stage CKD.

Characteristics of gout patients according to the laterality of nephrolithiasis: A cross-sectional study using helical computed tomography.

OBJECTIVE: To clarify the clinical and laboratory characteristics of nephrolithiasis in gout by computed tomography (CT). METHODS: In 350 gout patients, unenhanced CT was performed at the 1st visit to hospital. Calculus density spots exceeding 1 mm in diameter with a CT value >120 Hounsfield units in the kidneys were defined as kidney stones. The association between laterality and the number of stones was investigated in each stone carrier. The 350 patients were classified into three groups (bilateral, unilateral and non-stone carriers). Then serum urate (Sua), renal function, uric acid metabolism, and the prevalence of metabolic syndrome (Mets) were compared among these groups by the Tukey-Kramer test or Fisher's exact test. RESULTS: Kidney stone(s) were detected in 108 (31%) of the 350 patients (bilateral in 58 and unilateral in 50). In 64 of the 108 patients (59%), there was no history of urolithiasis. Sua, serum creatinine and uric acid clearance were significantly higher (P = 0.001, P < 0.001, P = 0.043, respectively), while the estimated glomerular filtration rate was significantly lower (P = 0.039) in bilateral stone carriers than in non-stone carriers. No significant differences of uric acid metabolism or the prevalence of Mets were noted among the three groups. CONCLUSIONS: Approximately one-third of gout patients had kidney stones and more than half of the patients with stones were bilateral and multiple stone carriers. Elevation of Sua might increase the stone burden in gout, leading to more severe renal dysfunction. An association between nephrolithiasis and Mets was not demonstrated in gout patients.

Novel evaluation of nephrolithiasis as a complication of gout: a cross-sectional study using helical computerized tomography.

PURPOSE: We clarified whether the clinical profiles of patients with a history of urolithiasis (stone formers) truly reflect those of patients who currently have renal stones (stone carriers). MATERIALS AND METHODS: We evaluated 463 patients with gout using helical computerized tomography, urolithiasis history and relevant clinical parameters. RESULTS: Nephrolithiasis was observed in 157 of the 463 patients (34%) on helical computerized tomography but only 75 (16%) had a urolithiasis history. Of the 157 stone carriers 107 (68%) did not have a urolithiasis history. In those 157 patients serum urate and serum creatinine were higher than in the 306 nonstone carriers (p = 0.017), and the estimated glomerular filtration rate and urinary pH were lower (p = 0.0096 and 0.0249, respectively). However, there was no significant difference in laboratory findings between the 75 stone formers and 388 nonstone formers. Serum urate and creatinine were higher, and the estimated glomerular filtration rate and urine pH in bilateral stone carriers were lower than in unilateral stone carriers. According to HU density attenuation values on computerized tomography, an estimated third of the calculi that complicated 31 recent gout cases was uric acid. CONCLUSIONS: The concept of stone formers may lead to underestimating the prevalence of urolithiasis. Our analysis of stone carriers showed that a higher stone burden is associated with greater renal derangement, as determined by serum urate and creatinine, the estimated glomerular filtration rate and urine pH. To accurately clarify the correlation of gout and urolithiasis, it is advantageous to select stone carriers as subjects of study.