ABSTRACT
A commercially available enzyme-immunometric assay for serum alpha-glutathione S-transferase (GST) was evaluated. Endogenous serum alpha-GST diluted linearly within the calibration range. However, we recommend that the sample and second antibody reagent are always added sequentially in the assay to avoid hook effect. Between-assay variability was below 7% across the calibration range and the upper limit of the reference range in adults (n = 219) was 11.4 micrograms/L. Within-individual variability in serum alpha-GST concentrations measured over a 4-6 week period in 4 healthy adults was small. Serum alpha-GST concentrations did not change significantly 6 h after a therapeutic dose of paracetamol. Studies in two patients after liver transplantation showed that serum alpha-GST is a better discriminant of acute changes in liver function than conventional tests. Serum alpha-GST concentrations were unaffected by gross muscle damage, extrahepatic inflammation, or haemolysis and thus appear to be more liver specific than transaminase activities. The effect of renal impairment on serum alpha-GST concentrations requires further investigation.
Subject(s)
Glutathione Transferase/blood , Immunoenzyme Techniques , Acetaminophen/pharmacology , Alkaline Phosphatase/blood , Analgesics, Non-Narcotic/pharmacology , Analysis of Variance , Arthritis, Rheumatoid/enzymology , Bilirubin/blood , Evaluation Studies as Topic , Graft Rejection/immunology , Humans , Kidney Diseases/enzymology , Liver/enzymology , Liver Function Tests , Liver Transplantation , Longitudinal Studies , Reagent Kits, Diagnostic , Reference Values , Reproducibility of Results , Rhabdomyolysis/enzymology , Rheumatoid Factor/bloodABSTRACT
The wide hepatic distribution, high cytosolic concentration, and short in vivo plasma half-life of serum alpha-glutathione s-transferase are properties which may make monitoring this enzyme more clinically useful than conventional biochemical liver function tests as a marker of hepatocellular damage associated with acute liver allograft rejection. In a prospective longitudinal study of 58 liver transplants in 45 patients, serum alpha-glutathione S-transferase concentrations rose significantly more consistently and more rapidly than conventional liver function tests in association with acute rejection. However, a rise in alpha-glutathione S-transferase was less specific for rejection than conventional liver function tests although none of the tests had a positive predictive value for rejection of greater than 32%. Compatible with the particularly short in vivo plasma half-life of this enzyme, alpha-glutathione S-transferase concentrations fell to or toward normal more rapidly than conventional liver function test measurements following uncomplicated transplantation as well as during high-dose steroid treatment of rejection. This may be valuable, both in improving the resolution of biochemical changes associated with early rejection episodes and in determining when treatment of rejection has been successful. Further studies are warranted, however, to assess whether the fall in GST during rejection treatment does genuinely reflect the histological resolution of rejection.
