Objective To investigate the accuracy and comparability of alanine aminotransferase(ALT) measurement results in human serum samples and commercial materials before and after calibration with frozen human serum calibrator assigned by reference method. Methods Five frozen human-pooled serum samples were assigned values by the reference method without pyridoxal 5-phosphate for ALT in four candidate reference laboratories, which were used to evaluate the results of ALT catalytic activity detected by ten testing systems in Guangzhou. One of the serum sample was used as the common calibrator. The results of serum samples and commercial materials from different systems before and after calibration were analyzed for biases and intersystem variations. Results After calibration,the variance of the systems for the results of serum samples decreased from between 11. 90% and 8. 60% to between 6. 78% and 2. 30% ,and the bias decreased dramatically from between - 12. 52% and - 8. 44 % to between - 3. 36% and -0. 08%. Slopes of the regression lines of ALT results of serum samples between reference systems and routine systems after calibration were closer to 1 and intercepts closer to 0 than those obtained before calibration. Conclusion Accuracy and comparability of ALT measurements could be improved by using a common human serum calibrator. But commercial materials might not be commutable for human serum in ALT measurements.%目的 调查不同检测系统使用经参考方法赋值的冰冻人血清样本作为校准品进行校准后,不同来源样本丙氨酸氨基转移酶(ALT)测定结果的可比性与准确性的改变程度.方法 5份经4家候选参考实验室应用不含磷酸吡哆醛的ALT参考方法定值的冰冻人混合血清样本用于评价广州地区10个不同检测系统ALT催化活性结果的可比性与准确性.其中一个样本用作校准品校准各系统.比较校准前后各系统间新鲜血清样本与商品制备物测定结果的变异与偏倚.结果 校准后,各检测系统间新鲜血清测定结果的变异由11.90%～8.60%下降到6.78%～2.30%,偏倚则从-12.52%～-8.44%下降到-3.36%～-0.08%.校准后,常规系统测定新鲜血清结果与参考方法的回归曲线的斜率和截距比校准前更接近1和0;而商品制备物测定结果校准后的斜率和截距则无明显改善.结论 采用定值冰冻人血清样本作为校准品可以改善不同检测系统测定结果的准确性和可比性,但由于基质效应的存在不能改善商品制备物测定结果的可比性.
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