Serum 25-hydroxyvitamin D status of a large Chinese population from 30 provinces by LC–MS/MS measurement for consecutive 3 years: differences by age, sex, season and province

Kai Bai, Heng Dong, Ling Liu, Xuhui She, Chang Liu, Mujun Yu, Zhihui Liang, Haibiao Lin, Peifeng Ke, Xianzhang Huang, Xinzhong Wu, Qiaoxuan Zhang, Beibei Zhao