运用生化分析仪反应曲线吸光度差异计算高浓度天冬氨酸氨基转移酶的值

摘要

目的 运用生化分析仪反应曲线上呈线性段的吸光度变化直接计算高浓度天冬氨酸氨基转移酶(AST)活力.方法 当标本中AST浓度过高时,往往由于底物耗尽导致仪器测不出结果,可以选择适当的已知浓度AST作为对照,利用AST反应曲线,运用公式计算AST的浓度:AST值(U/L)=[△A(计算)/ △A(对照)] ×对照物的浓度,可以计算出高浓度AST的值.结果 直接计算的值和通过稀释后再测的值相对偏差小于10%,符合美国临床检验修正法规1988(CLIA.'88)许可范围,证明AST的计算值可以作为临床参考.结论当仪器直接检测高浓度AST,由于超线性范围而测不出结果,但临床又急需报告或标本量不足不能稀释重测时,可以运用生化反应曲线直接计算出结果,及时发放报告.%Objective This experiment intended to directly calculate the activity of aspartate aminotransferase ( AST ) with a high concentration based on the absorbance changes presented by the linear section on the reaction curve of a biochemical analyzer. Methods When biochemical analyzer failed to detect very high concentration of AST in the samples due to the depletion of substrates, the value of high concentration of AST was determined with the use of known concentrations of AST as the control, and AST reaction curve. AST concentration was calculated with the formula : AST value (U/L) = [ A A ( calculated )/ A A ( control) J ] x concentration of the control. Results The relative deviation between the directly calculated value and the calculated value after the dilution was less than 10% , which was consistent with the CLIA 88 permission scope. Therefore, the calculated value of AST was verified competent as clinical references. Conclusion When the biochemical analyzer is directly used to detect AST with a high concentration or the retest is not available due to insufficient sample volume, the results are undetectable due to the surpassed linear range and fail to meet the urgent clinical need. Under such circumstances, the biochemical reaction curve can be directly used to calculate the results for a timely report.