Relation of Age, Sex and Bone Mineral Density to Serum 25‐Hydroxyvitamin D Levels in Chinese Women and Men

Objective To investigate the relation of circulating 25‐hydroxyvitamin D (25[ OH ] D ) levels to age, sex, and bone mineral density ( BMD ) in adults living in Guangzhou Province. Methods This cross‐sectional study comprised 188 women and 122 men aged 17–88 years who were randomly sampled among community‐dwelling Guangzhou residents. BMD at the lumbar spine and femoral neck was measured by dual energy X‐ray absorptiometry, and serum concentrations of 25( OH )D, parathyroid hormone ( PTH ), procollagen I N ‐terminal peptide, and beta C ‐telopeptide of collagen were assayed by electrochemiluminescence immunoassay. Serum 25( OH )D concentrations were divided into four subgroups: severe deficiency (<10 ng/mL), deficiency (10–20 ng/mL), insufficiency (20–30 ng/mL), and sufficiency (≥30 ng/mL). Results The mean age of participants was 47.39 ± 19.32 years. Serum 25( OH )D levels were significantly lower in women than men (25.35 ± 6.59 ng/mL vs 27.25 ± 7.94 ng/mL, P < 0.05). The prevalence of 25( OH )D severe deficiency (<10 ng/mL) was 1.6% in men, zero in women; 25( OH )D deficiency (10–20 ng/mL) was 22.9% in women and 20.5% in men; and 25( OH )D insufficiency (20–30 ng/mL) was 73.4% in women and 65.6% in men. An inverse relationship between serum 25( OH )D levels and age ( r = −0.249, P < 0.01) was observed in men, but no correlation was found in women ( r = 0.130, P > 0.05). Serum 25( OH )D levels were positively associated with lumbar spine and femoral neck BMD ( r = 0.382, P < 0.01; r = 0.384, P < 0.01, respectively) in elderly women and ( r = 0.332, P < 0.05; r = 0.260, P < 0.05, respectively) and in young men. When adjustments were made for age, correlations between serum 25( OH )D levels and lumbar spine and femoral neck BMD persisted ( r = 0.325, P < 0.05; r = 0.323, P < 0.05, respectively) in elderly women. However, age‐adjusted serum 25( OH )D levels were positively correlated with BMD at lumbar spine ( r = 0.278, P < 0.05) but not at femoral neck ( r = 0.165, P > 0.05) in young men. No association between unadjusted or age‐adjusted serum 25( OH )D levels and lumbar spine and femoral neck BMD was found in young and middle‐aged women and in middle‐aged and elderly men. Neither serum PTH levels nor bone turnover markers were related to unadjusted and age‐adjusted serum 25( OH )D levels in our participants. Conclusion More than two‐third of participants residing in Guangzhou had vitamin D insufficiency. Serum 25( OH )D level is an important biomarker for BMD in elderly women and young men.