Vitamin D levels, vitamin D supplementation, and prognosis in patients with chronic kidney disease .

BACKGROUND

Vitamin D (Vit D) deficiency plays a central role in the pathogenesis of chronic kidney disease (CKD) complications, both skeletal and nonskeletal. The purpose of this study was to examine whether 25(OH)D levels and supplementation with oral cholecalciferol (Vitamin D3 (Vit D3)) are associated with morbidity and mortality among patients with significant CKD.

METHODS

CKD patients attending the nephrology clinic at Shaare Zedek Medical Center between July 1, 2008 and January 31, 2012, tested at least twice for 25(OH)D levels, were enrolled. Primary endpoints included death, end-stage renal disease (ESRD) requiring start of dialysis, a rise of at least 50% in serum creatinine, or composite endpoints of the above.

RESULTS

A total of 516 patients were studied, of whom 178, 257, and 81 patients had baseline vitamin D levels < 5 ng/mL, 15 - 30 ng/mL, and > 30 ng/mL, respectively. We found an association between baseline 25(OH)D level below 15 ng/mL and renal outcomes (start of dialysis or a rise of at least 50% in serum creatinine) in both crude and multivariate analyses (hazard ratio (HR) 3.17, 95% CI 1.12 - 8.94). Vit D3 supplementation demonstrated beneficial effects on combined renal outcomes and death in univariate analyses (p = 0.02). Moreover, an increment of 10 ng/mL in 25(OH)D levels was associated with a 25% reduction in mortality (HR 0.755 (95% CI 0.54 - 1.00), in crude but not adjusted analyses.

CONCLUSIONS: Significant Vit D deficiency in CKD can serve as a biological marker indicating patients in whom adverse renal outcomes can be anticipated. Moreover, Vit D3 supplementation and rise of serum 25(OH)D levels may have beneficial influence on hard renal outcomes.
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