[Serum levels of 25-hydroxyvitamin D in normal Beijing subjects].

This report describes the changes of serum Ca, P, ALP and 25-OH D3 (using protein binding assay) with age in 592 normal Beijing subjects, aged 0-87 years old. The results were: (1) There was highly negative correlation between age and 25-OH D3 (r = -0.380, P less than 0.01), especially after 41 years old, less between age and ALP and least with P and Ca. (2) There was a significant sex difference of 25-OH D3 and ALP (P less than 0.05). Their serum levels were higher in the male than in the female, indicating that the female is easier to suffer from metabolic bone disease than the male after 41 years of age. (3) There was a distinct seasonal variation in serum 25-OH D3 levels, which were lower in winter and Spring than in Summer and Autumn (P less than 0.001), indicating that there is a greater possibility of Vitamin D deficiency in Winter and Spring.