Biological variation and the effect of fasting and halothane anesthesia on plasma glutathione S-transferase concentrations.

Using a specific RIA, we have investigated in patients and volunteers whether fasting, diminished hepatic clearance, hemoconcentration, or within-day biological variation might be responsible for the transient increases in plasma glutathione S-transferase (GST) concentration observed after anesthesia. GST concentration was measured in 44 healthy volunteers after an overnight fast and at 3, 6, and 24 h after the fasting sample. The concentration was significantly lower at 3 and 6 h after than in the fasting sample (P = 0.0019 and P = 0.015, respectively). The change in GST concentration caused by fasting was examined in 30 subjects by comparing pre- and postfasting values. Fasting had no significant effect on GST concentration overall (P = 0.4721), but two individuals showed a marked increase in GST concentration after fasting overnight. In a separate study of 10 patients, plasma amylase activity and plasma concentrations of GST and albumin were measured immediately before and 3 h after induction of halothane anesthesia. Although GST concentration was increased at 3 h in each of the 10 patients, plasma amylase activity and plasma albumin concentration were significantly decreased in all patients (P = 0.002). Apparently, increases in GST concentration after anesthesia do not result from incidental factors.