Gundberg C M, Markowitz M E, Mizruchi M, Rosen J F
J Clin Endocrinol Metab. 1985 Apr;60(4):736-9. doi: 10.1210/jcem-60-4-736.
Osteocalcin, the vitamin K-dependent protein synthesized in bone, is found in blood. The level of circulating osteocalcin has recently been used as an indicator of the rate of bone turnover. We measured serum osteocalcin during 24-h periods in 6 normal 20- to 30-yr-old men and 4 women. Blood was sampled via an indwelling venous catheter every 30 or 60 min for 24 h. Circadian rhythmicity in circulating osteocalcin was found in 9 of the 10 individuals studied. Osteocalcin levels fell during the morning, rose in the afternoon and early evening, and reached a peak nocturnally. There were no consistent correlations between osteocalcin concentrations and circulating levels of ionized calcium, total calcium, or inorganic phosphate in the subjects tested. This study illustrates the importance of regulating the time of blood sampling for osteocalcin determinations in clinical investigations of metabolic bone disease.
骨钙素是一种在骨骼中合成的维生素K依赖蛋白，存在于血液中。循环骨钙素水平最近被用作骨转换率的指标。我们在6名年龄在20至30岁的正常男性和4名女性中，在24小时内测量血清骨钙素。通过留置静脉导管每30或60分钟采集一次血样，持续24小时。在所研究的10名个体中，有9名发现循环骨钙素存在昼夜节律。骨钙素水平在早晨下降，在下午和傍晚早期上升，并在夜间达到峰值。在受试对象中，骨钙素浓度与离子钙、总钙或无机磷酸盐的循环水平之间没有一致的相关性。这项研究说明了在代谢性骨病的临床研究中，规范骨钙素测定血样采集时间的重要性。
