Vitamin D Research Today is a free monthly online journal that collates and summarizes the latest research about Vitamin D, including details on sources, melanin, benefits, deficiency, supplements, calcium absorption.

25-Hydroxyvitamin D levels and albuminuria in the Third National Health and Nutrition Examination Survey (NHANES III).

de Boer IH, Ioannou GN, Kestenbaum B, Brunzell JD, Weiss NS

Division of Nephrology, University of Washington, Seattle, WA 98117, USA. deboer@u.washington.edu <deboer@u.washington.edu>

BACKGROUND: Albuminuria is a risk factor for chronic kidney disease progression, end-stage renal disease, cardiovascular events, and mortality. Animal studies suggested that vitamin D insufficiency may contribute to the pathogenesis of albuminuria. STUDY DESIGN: Cross-sectional study. SETTING & PARTICIPANTS: 15,068 adults participating in the Third National Health and Nutrition Examination Survey. PREDICTOR: Serum 25-hydroxyvitamin D concentration, examined in quartiles. OUTCOMES & MEASUREMENTS: Albuminuria, defined using established sex-specific cutoff values for urine albumin-creatinine ratio (25 to 2,999 mg/g for women, 17 to 2,999 mg/g for men). RESULTS: A stepwise increase in the prevalence of albuminuria was observed with decreasing quartiles of vitamin D concentration: 8.9%, 11.5%, 13.7%, and 15.8% (P < 0.001). Adjusting for age, sex, race/ethnicity, region and season of measurement, smoking status, body mass index, and estimated glomerular filtration rate, relative risks for albuminuria by decreasing quartile of vitamin D concentration were 1.00 (reference group), 1.14 (95% confidence interval, 0.95 to 1.37), 1.22 (95% confidence interval, 1.03 to 1.45), and 1.37 (95% confidence interval, 1.10 to 1.71; P = 0.006). Additionally adjusting for blood pressure and diabetes mellitus, these risks were somewhat attenuated and retained statistical significance. LIMITATIONS: The cross-sectional design of this study does not allow demonstration of temporal or causal relationships between vitamin D and albuminuria. CONCLUSIONS: Additional studies are needed to clarify the relationship of vitamin D with albuminuria and determine whether vitamin D therapy prevents or improves markers of kidney and cardiovascular disease.

Published 26 June 2007 in Am J Kidney Dis, 50(1): 69-77.
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