The difference in BMD distribution between genders may be explained by the differences in endocrine and paracrine factors, and the rapid decrease of sex steroid levels in postmenopausal women aggravates the bone loss.17 In addition, we found that the level of Apelin-13 was negatively related to age, demonstrating the risk of osteoporosis may be added with age, this conclusion was consistent with previous studies.17 The gene discussed is APLN; the disease is osteoporosis.