Age-related changes of serum tartrate-resistant acid phosphatase 5b and the relationship with bone mineral density in Chinese women

Osteoclastic activity is mainly assessed by measurement of urinary markers (eg C-terminal cross-linked telopeptides of type I collagen, N-terminal cross-linked telopeptides of type I collagen etc), the levels of which could often be affected by renal clearance. Recently, serum tartrate-resistant acid phosphatase 5b (TRACP5b) has been used as an alternative serum marker to evaluate osteoclastic activity. We investigated the age-related changes of TRACP5b level and its association with bone mineral density (BMD) in Chinese women. Seven-hundred and twenty-two Chinese mainland women aged 20–79 years were recruited in the study. Serum TRACP5b level was measured using immunoassay to evaluate the state of bone resorption. Bone mineral density (BMD) (g/cm2) at lumbar spine 1–4 and proximal femur were measured by duel-energy X-ray absorptiometry. The serum TRACP5b level reached a bottom value in premenopausal women aged 30–39, gradually increased in women aged 40–49, rapidly rose in women aged 50–59, and culminated with a maximum value in women aged 60–69 before a slow drop in women aged 70–79. The average level of TRACP5b was significantly higher in postmenopausal women [(3.29±1.07) U/L] than in premenopausal women ([1.70±0.59] U/L). The levels of TRACP5b were inversely correlated with BMD at all measured sites (P