Objective   To investigate the seasonal variation of 25-hydroxyvitamin D〔5(OH)D〕and vitamin Kin elderly people.

  Methods   Plasma 25(OH)D and parathyroid hormone(PTH)of 85 healthy elderly volunteers were measured by radioimmunoassays in spring and autumm.Plasma vitamin Kwere measured by HPLC.

  Results   The concentration of vitamin K in wowen were significant higher than those in men both spring and autumn, whereas there were no seasonal differences in the concentration of vitamin K of women and men.The concentrations of 25(OH)D in autumn were signincant higher than those in spring.No differences in the concentrations of 25(OH)D between women and men in the same season were found.The rates of vitamin D deficiency were 63.4%, 7.3% and 65.9% for women in spring, women in autumn and men in spring respectively.The rate of vitamin D deficiency in spring was significant higher than that in autumn.The concentrations of PTH in autumn were significant lower than those measured in spring.A negative association between PTH and 25(OH)D was found in women in spring(r=-0.426, P < 0.01).

  Conclusion   There were seasonal variations in plasma 25(OH)D and PTH in elderly people living in Shenyang.Vitamin D levels in this population were low in early spring.There were seasonal variations in plasma vitamin K in this population.