Effects of Age and Renal Function on Vitamin D Status in Men

In general, no study has examined the relationship between vitamin D status and key parameters of bone mineral homeostasis in healthy men in Iran. The effects of age and renal function on vitamin D status were determined in a cross-sectional study on a healthy population of Iranian men. From January through February 2001, 520 men, aged 20 – 74 years were selected through a cluster randomized sampling from Shiraz. Serum 25-hydroxyvitamin D, intact parathyroid hormone, calcium, phosphorus, alkaline phosphatase, creatinine, and albumin were measured. Pearson and partial correlation coefficients were used to determine the association between variables. Five hundred twenty men with a mean±SD age of 45±15 years and a mean±SD 25-hydroxyvitamin D level of 35±17 nmol/L were enrolled into the study. Over 33.9% of men in Shiraz had a low level of 25-hydroxyvitamin D (≤25 nmol/L). Serum 25-hydroxyvitamin D did not decline with age in men. Serum parathyroid hormone increased significantly by age in men, but it did not correlate with the decline in creatinine clearance. Men had a decline in serum phosphorus (r=0.23, P<0.0001) and calcium (r=0.14, P=0.001) concentrations by age. Creatinine clearance declined with age. In healthy men, the serum level of 25-hydroxyvitamin D did not decline with age. Nonetheless, the prevalence of vitamin D deficiency is high which warrants consideration of dietary vitamin D supplement in men.