Department of Medical Laboratory Sciences, University of Delaware, Newark, Delaware; Diabetes and Metabolic Research Center, Christiana Care Health System, Newark, Delaware.
Surg Obes Relat Dis. 2013 Nov-Dec;9(6):950-5. doi: 10.1016/j.soard.2012.08.006. Epub 2012 Aug 24.
Osteocalcin (OC), a protein synthesized by osteoblasts, is a marker of bone turnover with undercarboxylated OC (ucOC) being involved in glucose homeostasis. Although laparoscopic Roux-en-Y gastric bypass (LRYGB)-induced weight loss likely alters bone turnover, data on markers of bone turnover remain less clear. The aim of this study was to examine the effect of surgically induced weight loss on OC and ucOC.
A total of 32 individuals with a body mass index 50.2±10.2 kg/m(2) underwent LRYGB. Osteocalcin, ucOC, other blood analytes (e.g., vitamin D, leptin, total and high-molecular-weight adiponectin), and homeostasis model assessment for insulin resistance were measured before and after weight loss. The effect of an acute nutrient load on OC parameters after a mixed meal tolerance test also was assessed.
Six months after surgery, there was an increase in OC (17.8±7.4 [mean±SD] [baseline] versus 31.5±9.8 ng/mL [follow-up]; P<.001) and ucOC (7.3±6.2 versus 18.5±8.9 ng/mL; P<.001). Although adiponectin increased, only the magnitude of change in OC and leptin was correlated (r =-.43; P = .017). After weight loss, an acute nutrient load reduced OC (31.5±9.8 [0-hour] versus 29.6±8.2 [2-hour] ng/mL; P = .024), whereas ucOC was higher (18.8±9.3 [0-hour] versus 21.1±8.6 [2-hour] ng/mL; P< .001).
Surgically induced weight loss was associated with increases in OC and ucOC. Underlying mechanisms are unclear, but change in OC may be related to change in leptin. After a nutrient load, the increase in ucOC suggests a potential role as a short-term compensatory regulator of glucose homeostasis.
骨钙素（OC）是成骨细胞合成的一种蛋白质，是骨转换的标志物，其中未羧化的 OC（ucOC）参与血糖稳态。虽然腹腔镜 Roux-en-Y 胃旁路术（LRYGB）引起的体重减轻可能会改变骨转换，但有关骨转换标志物的资料仍不够明确。本研究旨在探讨手术引起的体重减轻对 OC 和 ucOC 的影响。
共有 32 名 BMI 为 50.2±10.2 kg/m2 的个体接受了 LRYGB 手术。在体重减轻前后测量了 OC、ucOC、其他血液分析物（如维生素 D、瘦素、总和高分子量脂联素）和胰岛素抵抗的稳态模型评估。还评估了混合餐耐量试验后急性营养负荷对 OC 参数的影响。
手术后 6 个月，OC（17.8±7.4 [均值±SD] [基线] 与 31.5±9.8 ng/mL [随访]；P<.001）和 ucOC（7.3±6.2 与 18.5±8.9 ng/mL；P<.001）均增加。尽管脂联素增加，但只有 OC 和瘦素的变化幅度呈相关（r =-.43；P =.017）。体重减轻后，急性营养负荷降低了 OC（31.5±9.8 [0 小时] 与 29.6±8.2 [2 小时] ng/mL；P =.024），而 ucOC 更高（18.8±9.3 [0 小时] 与 21.1±8.6 [2 小时] ng/mL；P<.001）。
手术引起的体重减轻与 OC 和 ucOC 的增加有关。其潜在机制尚不清楚，但 OC 的变化可能与瘦素的变化有关。在营养负荷后，ucOC 的增加表明其可能作为血糖稳态的短期代偿调节因子发挥作用。
