The effect of pre-incubation and direct procedure for the alanine transaminase assay in two kits compared

The kinetic measurement of serum alanine transaminase was carried out on two enzyme kits (Roche and Calbiochem), done as a direct method and a pre-incubation method. Variable results from commercial control sera and patient sera by these four procedures were obtained. Pre-incubation enzyme values were generally lower than the direct values (mean difference 10%), but there were marked differences between the results from the two kits. This finding has important significance especially for laboratories participating in external QC Programmes. Frequent precision checks of the method and a local reference range are therefore necessary.