男性骨生化指标随年龄的变化及其与骨密度的关系

目的探讨男性人群骨生化指标,血清骨特异性碱性磷酸酶(sBAP)、血清骨钙素(sOC)和Ⅰ型胶原氨基末端肽(sNTX)随年龄变化及其与骨密度(BMD)之间的关系。方法用ELISA测定389例20-80岁健康男性sBAP、sOC和sNTX;用DXA仪测定腰椎及髋部BMD。结果(1)sBAP、sOC和sNTX与年龄呈负相关,3个骨生化指标随年龄的变化均以三次回归模型的拟合程度最佳,拟合曲线的决定系数(R2)为0．013-0．029(P<0．05)。(2)按每10岁年龄段分组发现sBAP,sOC和sNTX的水平在20-29岁年龄段最高,分别为31 U／L±13 U／L、13μg／L±6μg／L、18μmol／L±7μmol／L;随年龄的增长而降低;50-59岁年龄段达最低值分别为27 U／L±9 U／L、9μg/L±5μg/L、16μmol／L±6μmol／L。60岁之后骨吸收指标sNTX轻度增加为16μmol／L±6μmol／L,而骨形成指标则保持相对稳定。(3)校正年龄、身高、体重、体重指数及吸烟后的偏相关分析显示:sBAP与各部位BMD呈负相关;除腰椎侧位外,sOC与其他各部位BMD均呈负相关;而sNTX与腰椎正位AP(L1-L4)及髋部整体BMD负相关。结论敏感性、特异性较强的骨转换指标如sBAP、sOC和sNTX随男性年龄而变化,且与BMD呈负相关。

Age-related change of bone biochemical markers and their relationships to mineral density in healthy Chinese men

OBJECTIVE: To study the age-related changes of bone formation markers, i.e., serum bone alkaline phosphatase (sBAP) and serum osteocalcin (sOC), bone resorption marker, i.e., cross-linked N-telopeptides of type 1 collagen (sNTX), and bone mineral density (BMD) in healthy men. METHODS: Serum sBAP, sOC, and sNTX of 389 randomly selected males, aged 20 - 80, all of Han nationality, were measured by using enzyme-linked immunosorbent (ELISA). Dual energy X-ray densitometer was used to measure the BMD of the lumbar vertebrae, left femoral neck, Ward's triangle, and hip. The relationships of these markers to age were analyzed. RESULTS: (1) The sBAP, sOC, and sNTX were negatively correlated with age, the cubic regression model being better with age-related changes of bone biochemical markers as compared with the other regression models (R(2) = 0.013 - 0.029, P < 0.05); (2) When all subjects were stratified by 10-years, the bone biochemical marker values were the highest in the age group 20 - 29, with the sBAP of 30.9 U/L +/- 12.6 U/L, sOC of 12.6 microg/L +/- 6.2 microg/L, and sNTX of 18.2 micromol/L +/- 6.6 micromol/L; then decreased with aging and to a nadir level in the age group 50 - 59, with the sBAP of 26.9 U/L +/- 8.6 U/L, sOC of 9.2 microg/L +/- 5.3 microg/L, and sNTX of 15.6 micromol/L +/- 6.1 micromol/L. After the age of 60, sNTX increased slightly 16.0 micromol/L +/- 6.1 micromol/L, however, BAP and sOC remained stable; (3) After adjustment for age, height, weight, BMI and smoking, serum BAP was negatively correlated with BMD of multiple skeletal sites. sOC was inversely associated with BMD of multiple skeletal sites except lateral spine; and sNTX was negatively correlated with BMD of the lumbar spine and total hip. CONCLUSION: Negatively correlated with BMD, sBAP, sOC, and sNTX may be sensitive and relatively specific markers to evaluate age-related changes of bone turnover.