Gamma-glutamyl transferase

Method

Serum gamma-glutamyl transferase catalytic activity by clinical enzymatic assay, reported in international units per litre. The assay temperature and reference method are recorded on the edge.

The method is part of the endpoint identity. Studies measuring the same quantity by a different method are held as separate endpoints.

Notes

Near-misses are serum alanine aminotransferase and aspartate aminotransferase, reported in the same liver panel, in the same units, falling with benefit for the same interventions. The distinction is mechanistic: this is a CHOLESTATIC marker, sensitive to alcohol and to enzyme induction, not a hepatocellular leakage marker, and it is the least specific of the three - it was null in PMID 41515249 while alanine aminotransferase fell. Substituting it for the transaminases weakens a real hepatocellular signal. Distinct also from adjudicated hepatotoxicity incidence, which is an event proportion in risk-ratio units.