Urinary Sulfate, Kidney Failure, and Death in CKD: The African American Study of Kidney Disease and Hypertension. Issue 7 (28th July 2022)

• Record Type: Journal Article
• Authors: Azim, Aniqa; Murray, Jennifer; Beddhu, Srinivasan; Raphael, Kalani L.
• Is Part Of: Kidney360. Volume 3:Issue 7(2022)
• Page Start: 1183
• Page End: 1190
• Publication Date: 2022-07-28
• Subjects: chronic kidney disease -- AASK (African American Study of Kidney Disease and Hypertension) -- bicarbonate -- chronic kidney disease -- chronic metabolic acidosis -- CKD progression -- dietary acid load -- dietary alkali load -- end stage kidney disease -- hypertension -- protein intake -- sulfate -- sulfur; 616.61
• DOI: 10.34067/KID.0000322022
• Languages: English
• ISSNs: 2641-7650

Abstract

Key Points: Higher urine sulfate levels were associated with more favorable outcomes in Blacks with kidney disease attributed to hypertension. These findings are independent of dietary protein intake, suggesting that sulfate has an effect on health above and beyond protein intake. Visual Abstract: Abstract : Background: Sulfur is an important mineral element whose principal source is animal protein. Animal protein contributes to the daily acid load, which is associated with poor outcomes in individuals with chronic kidney disease (CKD). We hypothesized that higher urinary sulfate, as a reflection of the daily acid load, is associated with a greater risk of death and CKD progression. Methods: Urinary sulfate was measured in 1057 African American Study of Kidney Disease and Hypertension (AASK) participants at baseline. Participants were categorized by tertiles of daily sulfate excretion. The longitudinal outcome of interest was the composite of death, dialysis, or 50% reduction in measured glomerular filtration rate (GFR). Multivariable adjusted Cox regression models were fit to relate the composite outcome to daily sulfate excretion using the lowest tertile as the reference. Results: Participants in the highest urinary sulfate tertile were more likely to be men and have a higher body mass index, protein intake, measured GFR, and urinary ammonium and phosphate excretion, and lower urinary protein/creatinine. Compared with those in the lowest tertile of sulfate, those in the highest tertile had a 44% lower hazard (95% CI, 0.37 to 0.84), and those in the middle tertile had a 27% lower hazard (95% CI, 0.55 to 0.96) of death, dialysis, or 50% reduction in measured GFR during follow-up after adjusting for demographics, GFR, protein intake, and other potential confounders. Protein intake was not associated with risk of these events. Conclusions: Higher urinary sulfate excretion is associated with more favorable outcomes in Blacks who have CKD attributed to hypertension.