Clinical implications of differences between two recommended procedures for determination of aspartate aminotransferase.

We compared two officially recommended methods for determination of aspartate aminotransferase (EC 2.6.1.1): that of the International Federation of Clinical Chemistry (IFCC) and that of the Deutsche Gesellschaft für Klinische Chemie (DGKC). We used automated enzyme analyzers, initiating the reactions with 2-oxoglutarate. Normal values, 10-30 U/L (IFCC) and 7-18 U/L (DGKC), were apparently insensitive to intra-individual variations. Samples obtained from patients with heart disease showed a markedly different amount of activation with pyridoxal phosphate as compared with samples from other patient categories. Ratios for aspartate aminotransferase/alanine aminotransferase, as used in the differentiation of liver disease, can still be used with either method for determination of aspartate aminotransferase.