The Impact of Duration of Menopause on Bone Metabolism in Detecting and Preventing Osteoporotic Fractures

Abstract

Background: Menopause accelerates bone loss after 10 years of cessation of the menstrual cycle causing osteoporosis. Hip fractures among postmenopausal women escalate morbidity and mortality in these women. Objective: The study was done to evaluate the effect of duration of menopause on BTMs so that it could detect post-menopausal osteoporosis at the earliest and predict the fracture risk Materials and Methods: The study was conducted in a tertiary hospital in Mangalore on 100 postmenopausal women. The duration of menopause was divided into quartiles. Evaluation and correlation of serum osteocalcin, urinary hydroxyproline, BMI, calcium, phosphorous and alkaline phosphatase was done on the duration of menopause. The subjects comprised 50 osteoporotic and 50 non-osteoporotic post-menopausal women. Continuous variables were represented as median and interquartile ranges. Comparison between two groups was done using the Mann Whitney U test. Comparison between more than two groups was done using the Kruskal Wallis test. The correlation was done using spearman’s correlation test. Statistical significance was considered at p<0.05. Results: Serum osteocalcin levels significantly declined and urinary hydroxyproline levels elevated between quartiles of duration of menopause in the entire study group and in osteoporotic women. (p<0.001). There was no significant difference in osteocalcin and hydroxyproline levels between the quartiles in the fracture group. 82% of the osteoporotic had >15 YSM. Conclusion: Osteocalcin levels plateaued after 8years of menopause and started decreasing after 15 YSM. Osteoporotic fractures were higher in more than 15 YSM and the osteocalcin level was 2.47 ng/ml in this quartile. There is no significant difference in osteocalcin levels in those with fractures, indicating no significance of screening for serum osteocalcin levels once the fractures have occurred. Hence concluding that the duration of menopause is the key indicator for osteoporosis and serum osteocalcin is a potent biomarker for detection of the risk of fracture. Monitoring of serum osteocalcin levels(<2.55ng/ml) after 8 years of menopause is very essential for early prophylactic treatment in order to prevent osteoporotic fractures and the burden associated with it. KEYWORDS: Duration of menopause, osteocalcin, quartiles, urinary hydroxyproline, osteoporotic fractures