Relationship between gamma-glutamyl transpeptidase and mean urinary alcohol levels in alcoholics while drinking and after alcohol withdrawal.

In 42 patients with alcoholic liver disease in whom daily urinary ethanol concentrations were measured for 3 months, after an abstinence of at least 1 month, serum gamma-glutamyl transpeptidase (GGT) activity was found to correlate (r = 0.69; p less than 0.0001) with mean urinary alcohol levels. The half-life of serum GGT decay in 32 patients who remained abstinent for an 8-week period was calculated to be 26 days. This prolonged half-life can result in high serum GGT levels in patients abstinent for prolonged periods, in whom serum GGT baselines before abstinence were very high. Individual variations in serum GGT levels should be interpreted in relation to continued alcohol consumption, keeping in mind the long half-life for this enzyme in these patients.