Butanol Extraction of Serum and Urinary Gamma-Glutamyltransferase and its Application in Clinical Diagnosis

Abstract

Summary Gamma-glutamyltransferase (γ-GT) activity was measured in serum and urine before and after extraction with n-butanol. Residual γ-GT activity after extraction of normal serum with butanol was more than 75 %, whereas for normal urine the figure was less than 68 %. The loss of activity from urine was not affected by prior dialysis, and the stabilisation which resulted from adding bovine serum albumin at a concentration of 40 g/l did not approach the residual activity with normal serum. In patients with a variety of renal diseases, residual γ-GT activity in the urine after butanol extraction was inversely correlated with the creatinine clearance. Butanol extraction was performed on serum samples from 182 patients with a variety of diseases. Eighty-one per cent of patients with elevated γ-GT activities caused by hepatobiliary disease had an increased loss of activity after butanol extraction. By contrast, only 34 % of patients with increased γ-GT activities in whom there was no clinical or other biochemical evidence of hepatic disease, had increased loss of γ-GT activity after butanol. The reasons for differences between urinary and serum γ-GT in response to butanol, and the implications in interpreting serum γ-GT activities are discussed.