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


METHODS
Cross-sectional study.


METHODS
15,068 adults participating in the Third National Health and Nutrition Examination Survey.


METHODS
Serum 25-hydroxyvitamin D concentration, examined in quartiles.


METHODS
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.


CONCLUSIONS
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.
de Boer
Ian H
IH
Division of Nephrology, University of Washington, Seattle, WA 98117, USA. deboer@u.washington.edu <deboer@u.washington.edu>
Ioannou
George N
GN
Kestenbaum
Bryan
B
Brunzell
John D
JD
Weiss
Noel S
NS
D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000419:Albuminuria / Q000150:complications / Q000453:epidemiology* / Q000208:ethnology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D015995:Prevalence; D012016:Reference Values; D012621:Seasons; D014481:United States / Q000453:epidemiology; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000150:complications / Q000453:epidemiology*
D014807:Vitamin D; C104450:25-hydroxyvitamin D