Liu G, Peacock M
Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA.
Calcif Tissue Int. 1998 Apr;62(4):286-9. doi: 10.1007/s002239900432.
The effect of the degree of carboxylation of osteocalcin (OC) on the properties of bone is unclear. The aim of this study was to relate serum concentrations of total OC (tOC) and undercarboxylated OC (ucOC), measured with a two-site immunoassay, to bone mineral density (BMD) at the femoral neck and ultrasonic transmitted velocity (UTV) at the os calcis in 257 women aged 60-99 years, 22 of whom had sustained a hip fracture. There was an increase in tOC (r = 0.19, P = 0.003) and ucOC (r = 0.20, P = 0.002) with age. No significant difference in tOC or ucOC between subjects with and without hip fracture was found. Serum tOC was negatively correlated with femoral neck BMD (r = -0.23, P = 0.0001) and os calcis UTV (r = -0.29, P = 0.0001) and partial correlations indicated that these relationships were independent of age. Serum ucOC also correlated negatively with os calcis UTV (r = -0.21, P = 0.001) and less strongly with femoral neck BMD (r = -0.13, P = 0.052). After adjusting for age, only the relationship between ucOC and os calcis UTV remained significant (r = -0.16, P = 0.017). It is concluded that in women over 60 years, the increase in tOC reflects an age-related rise in bone remodeling, whereas the increase in ucOC reflects an age-related fall in vitamin K status. The stronger relationship of ucOC with UTV than BMD suggests that the rise in ucOC may perhaps relate more to changes in bone quality than mineral content. Higher serum ucOC concentrations in subjects with a history of hip fracture could not be confirmed.
骨钙素（OC）的羧化程度对骨骼特性的影响尚不清楚。本研究的目的是通过两点免疫分析法测定257名60 - 99岁女性血清中总OC（tOC）和羧化不足OC（ucOC）的浓度，并将其与股骨颈骨矿物质密度（BMD）以及跟骨超声传播速度（UTV）相关联，其中22名女性曾发生髋部骨折。tOC（r = 0.19，P = 0.003）和ucOC（r = 0.20，P = 0.002）均随年龄增加。未发现有或无髋部骨折的受试者在tOC或ucOC方面存在显著差异。血清tOC与股骨颈BMD（r = -0.23，P = 0.0001）和跟骨UTV（r = -0.29，P = 0.0001）呈负相关，偏相关分析表明这些关系独立于年龄。血清ucOC也与跟骨UTV呈负相关（r = -0.21，P = 0.001），与股骨颈BMD的相关性较弱（r = -0.13，P = 0.052）。调整年龄后，仅ucOC与跟骨UTV之间的关系仍具有显著性（r = -0.16，P = 0.017）。研究得出结论，在60岁以上女性中，tOC的增加反映了与年龄相关的骨重塑增加，而ucOC的增加反映了与年龄相关的维生素K状态下降。ucOC与UTV的关系比与BMD的关系更强，这表明ucOC的增加可能与骨质量变化的关系比与矿物质含量的关系更大。有髋部骨折病史的受试者血清ucOC浓度较高这一情况未得到证实。
