Serum gamma-glutamyltransferase in a Swedish female population. Age-related reference intervals; morbidity and prognosis in cases with raised catalytic concentration.

We determined the catalytic concentration of gamma-glutamyltransferase in serum from a population sample of 1408 women in seven age strata between 26 and 72 years. The range in healthy individuals for the different age groups was found to increase with age with a maximum of the central 0.95 fractile interval at 58 years (0.17-1.68 μkat/1). The serum gamma-glutamyltransferase activity correlated with body mass index, blood pressure and concentrations of blood glucose and serum ferritin, triglycerides and cholesterol. During follow-up of women with gamma-glutamyltransferase activity >1.20 μkat/1, no woman developed any disease possibly related to the original finding of raised serum gamma-glutamyltransferase activity, several individuals being apparently healthy. Apparently, the serum gamma-glutamyltransferase assay is an unspecific indicator of several metabolic abnormalities. High values may be found in individuals in whom all commonly done investigations have given results within the health-associated reference interval.