Noonan K, Kalu M E, Holownia P, Burrin J M
Department of Clinical Biochemistry, St Bartholomew's School of Medicine and Dentistry, London, U.K.
Eur J Clin Chem Clin Biochem. 1996 Oct;34(10):841-4.
The apparent instability of measured osteocalcin has been reported as method-dependent and related to preanalytical variables such as storage temperature, and the use of anticoagulants and protease inhibitors. The aim of this study was to determine a sample collection procedure which minimised osteocalcin degradation. Blood samples from five normal individuals were collected with or without anticoagulants and protease inhibitors (heparin, EDTA, or heparin and aprotinin) and stored at 4 degrees C, -20 degrees C or -70 degrees C for up to 7 days, 28 days and 90 days respectively. Osteocalcin was measured by both a monoclonal EIA specific for intact osteocalcin and a bovine polyclonal RIA. Osteocalcin concentrations in serum and EDTA-treated samples significantly decreased by 40% (P < 0.001) with the ELISA and 72% (P < 0.001) with the RIA after 7 days storage at 4 degrees C. Similar falls were documented in these samples when stored at -20 degrees C and -70 degrees C and measured by the ELISA. Minimal changes in osteocalcin immunoreactivity were observed in either assay when heparin-treated plasma with or without aprotinin was stored at -20 degrees C or -70 degrees C for up to 90 days. The apparent instability of measured osteocalcin can be minimised using these conditions.
据报道，所测骨钙素明显的不稳定性取决于检测方法，并与诸如储存温度、抗凝剂和蛋白酶抑制剂的使用等分析前变量有关。本研究的目的是确定一种能将骨钙素降解降至最低的样本采集程序。采集了五名正常个体的血样，有的添加了抗凝剂和蛋白酶抑制剂（肝素、乙二胺四乙酸或肝素与抑肽酶），有的未添加，分别在4℃、-20℃或-70℃下储存长达7天、28天和90天。采用针对完整骨钙素的单克隆酶免疫分析和牛多克隆放射免疫分析两种方法检测骨钙素。在4℃储存7天后，采用酶联免疫吸附测定法时，血清和经乙二胺四乙酸处理的样本中的骨钙素浓度显著降低了40%（P<0.001），采用放射免疫分析法时降低了72%（P<0.001）。当在-20℃和-70℃储存并用酶联免疫吸附测定法检测时，这些样本中也出现了类似的下降情况。当含或不含抑肽酶的肝素处理血浆在-20℃或-70℃储存长达90天时，两种检测方法中骨钙素免疫反应性的变化均最小。采用这些条件可将所测骨钙素明显的不稳定性降至最低。
