Influence of years since menopause on bone mineral metabolism in South Indian women

BACKGROUND: Although an increase of bone turnover has been documented at the time of menopause, the subsequent abnormalities of bone resorption and formation in the elder women have not been investigated.
AIM: To assess bone turnover among different YSM (years since menopause) groups of postmenopausal women.
SETTINGS AND DESIGN: A case control study in a tertiary care hospital.
MATERIALS AND METHODS: Forty-seven premenopausal (control) women and 257 postmenopausal women were included in this study. Based on YSM, the postmenopausal women were divided into four groups namely, 1-5 YSM (n=82), 6-10 YSM (n=77), 11-15 YSM (n=58) and > 15 YSM (n=40). The levels of calcium, phosphorus, total alkaline phosphatase, FSH, LH, estradiol, intact-paratharmone and 25-hydroxy vitamin D in serum and urine levels of calcium, phosphorus and bone resorption marker calcium/creatinine(Ca/Cre) ratios were analyzed in all subjects.
STATISTICAL ANALYSIS USED: One way ANOVA followed by Duncan's multiple range test.
RESULTS: Significantly increased levels of FSH (P< 0.001) and declined levels of urine calcium (P=0.015) and Ca/Cre ratios (P=0.006) were observed in> 15 YSM group over 1-5 and 6-10 YSM groups. An inverse correlation was observed between serum FSH levels and urine Ca/Cre ratios (r = -0.655, P< 0.001) in> 15 YSM group. Comparable deficient estradiol levels were observed in all YSM groups.
CONCLUSIONS: The risk of bone resorption is greater in early years than late years of menopause. The decreased bone resorption risk in late postmenopausal women might be due to increased FSH levels. However, further studies are required to explore this finding.