The effect of cholecalciferol for lowering albuminuria in chronic kidney disease: a prospective controlled study

Growing evidence indicates that vitamin D receptor activation may have antiproteinuric effects. We aimed to evaluate whether vitamin D supplementation with daily cholecalciferol could reduce albuminuria in proteinuric chronic kidney disease (CKD) patients. This 6-month prospective, controlled, intervention study enrolled 101 non-dialysis CKD patients with albuminuria. Patients with low 25(OH) vitamin D [25(OH)D] and high parathyroid hormone (PTH) levels (n 50; 49) received oral cholecalciferol (666 IU/day), whereas those without hyperparathyroidism (n 51; 51), independent of their vitamin D status, did not receive any cholecalciferol, and were considered as the control group. Cholecalciferol administration led to a rise in mean 25(OH)D levels by 53.0 41.6 (P 0.001). Urinary albumin-to-creatinine ratio (uACR) decreased from (geometric mean with 95 confidence interval) 284 (189425) to 167 mg/g (105266) at 6 months (P 0.001) in the cholecalciferol group, and there was no change in the control group. Reduction in a uACR was observed in the absence of significant changes in other factors, which could affect proteinuria, like weight, blood pressure (BP) levels or antihypertensive treatment. Six-month changes in 25(OH)D levels were significantly and inversely associated with that in the uACR (Pearsons R 0.519; P 0.036), after adjustment by age, sex, body mass index, BP, glomerular filtration rate and antiproteinuric treatment. The mean PTH decreased by 13.8 20.3 (P 0.039) only in treated patients, with a mild rise in phosphate and calciumphosphate product [7.0 14.7 (P 0.002) and 7.2 15.2 (P 0.003), respectively]. In addition to improving hyperparathyroidism, vitamin D supplementation with daily cholecalciferol had a beneficial effect in decreasing albuminuria with potential effects on delaying the progression of CKD.