Low bone mass in urban Indian women above 40 years of age: prevalence and risk factors

Objective. To assess the prevalence and the relative importance of risk factors for low bone mass in Indian pre- and post-menopausal women. Methods. Data were collected on anthropometry and lifestyle factors in apparently healthy 80 pre- and 92 post-menopausal (40-75 years) women. Bone mineral density (BMD) was measured by dual energy X-ray absorptiometry. Fasting blood samples were analysed for Parathyroid hormone, vitamin D, calcium and zinc. Results. BMD at all three sites was significantly lower in post-menopausal than the pre-menopausal women (p < 0.001). Prevalence of osteoporosis was highest at the lumbar spine (25.8%) in post-menopausal women, while prevalence of osteopenia was high in pre-menopausal women (44.3%). Vitamin D deficiency was seen in 54.5% pre and 41.8% postmenopausal women and significant correlation of serum 25(OH) D levels (r = 0.16) was obtained only for total hip Z-score (p < 0.05). Correlation between sun index and lumbar spine BMD was marginally significant (r = 0.14, p = 0.07). Generalised linear models revealed that after adjusting for age, weight and height, percent decrease of 2.1-4.5% in BMD may be attributed to menopause. Conclusion. Age, weight, height, menopause, low intakes of calcium and low 25(OH)D along with poor sunlight exposure are the major factors contributing to bone loss in Indian women above 40 years of age.