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.

Hepatic manifestations of autoimmune rheumatic diseases

“…34 In a study of 98 patients with RA, 12 showed increases of both alkaline phosphatase and c-glutamyltransferase levels, but isoenzyme alkaline phosphatase studies disclosed that in three of seven patients, an increase in bone isoenzyme was responsible for the rise of alkaline phosphatase. In the others, the liver isoenzyme alone was raised, and in one patient, both were raised.…”

Influence of Detergents and Organic Solvent Extraction on Human Gamma-Glutamyltransferase Activity

“…(3) The mixture was centrifuged at 1,400 g for 5 min. (4) The lower (aqueous) layer was used for 7-GT activity, and the assay was performed within 30 min of butanol extraction (4). (5) 7-GT activity following butanol extraction was expressed as a percentage of the activity (of the diluted sample) prior to extraction.…”

Clinical Enzymology — a Perspective

“…The apparent molecular size of this fraction can be reduced by various treatments, so that it approaches that of the intermediate-sized form of the enzyme which predominates in serum. These treatments include extraction with organic sol vents or detergents, and so imply the presence of lipid components in the larger 7-glutamyl transferase complexes, a conclusion which has also been reached by other workers (29)(30)(31). It is not yet clear whether association of the enzyme with lipid results exclusively from the nature of its cellular environment or whether this association takes place, or is modified, after release of the enzyme into the circulation.…”