Kroll M H, Chesler R, Elin R J
Clinical Pathology Department, Warren G. Magnuson Clinical Center, National Institutes of Health, Bethesda, MD 20892.
Clin Chem. 1989 Jul;35(7):1523-6.
We studied the effect of lyophilization of serum pools on the determination of cholesterol with the enzymatic methods used in five automated analyzers: SMAC (Technicon), the RA-1000 (Technicon), the aca (Du Pont), the TDx (Abbott), and the Ektachem 700P (Kodak). We prepared two serum pools: pool A (2.2 g/L) and pool B (1.9 g/L). We separated each pool into three groups for treatment by lyophilizing or freezing at -20 and -70 degrees C. We determined cholesterol by the above methods at regular intervals during the next 270 days. For all methods, the measured concentration of cholesterol was less for the lyophilized serum than for frozen (P less than 0.007 by the paired-sample t-test). After adjusting for the dilutional effects of reconstitution, the decrease in original value was 0.7% for the SMAC, 1.7% for the RA-1000, 5.7% for the Ektachem, 9.4% for the TDx, and 14.3% for the aca. Lyophilization of cholesterol standards or serum samples may hamper the effective standardization of enzymatic methods and may be a source of apparent inaccuracy (bias) among enzymatic methods.
我们研究了血清混合液冻干对使用五种自动分析仪（SMAC（Technicon公司）、RA - 1000（Technicon公司）、aca（杜邦公司）、TDx（雅培公司）和Ektachem 700P（柯达公司））的酶法测定胆固醇的影响。我们制备了两个血清混合液：混合液A（2.2 g/L）和混合液B（1.9 g/L）。我们将每个混合液分成三组，分别通过冻干或在 - 20℃和 - 70℃冷冻进行处理。在接下来的270天内，我们定期使用上述方法测定胆固醇。对于所有方法，冻干血清中测得的胆固醇浓度均低于冷冻血清（配对样本t检验，P < 0.007）。在校正复溶的稀释效应后，SMAC的原始值降低了0.7%，RA - 1000降低了1.7%，Ektachem降低了5.7%，TDx降低了9.4%，aca降低了14.3%。胆固醇标准品或血清样本的冻干可能会妨碍酶法的有效标准化，并且可能是酶法之间明显不准确（偏差）的一个来源。
