A microtiter plate assay for measurement of serum alanine aminotransferase in blood donors.
Alanine aminotransferase (ALT) testing in blood donors is required in many countries as a surrogate test for viral hepatitis. Current automated ALT assays do not fulfill some operational requirements of blood banks. The standard ALT measurement method of the International Federation of Clinical Chemistry was adapted to the 96-well microtiter plate to obtain optimal conditions. The method was compared with a reference biochemical method using an analyzer on 251 serum samples. The analytical variability was minimal (2.3% for an ALT level of 59 IU/L and 3.6% for an ALT level of 33 IU/L) after a total analysis time of 8 minutes and a time of 7 minutes before the first reading. With these measures, a linear standard curve was obtained in the range of 10 to 130 IU per L.A computerized validation procedure allowed rejection of samples with high ALT levels. Comparison with the analyzer gave a correlation coefficient, r = 0.935. The method proved to be efficient and time-saving in routine use over an 8-month period. The microtiter plate ALT assay is helpful in allowing the simultaneous distribution of ALT and immunoenzymatic assays. It provides accurate results and a minimal risk of false-negative results.