INFLUENCE OF AGE AND BODY-MASS INDEX ON GAMMA-GLUTAMYL-TRANSFERASE ACTIVITY - A 15-YEAR FOLLOW-UP EVALUATION IN A COMMUNITY SAMPLE

Most clinicians and researchers view serum gamma-glutamyltransferase ( GGT) activity as a measure that can be interpreted equally in patients regardless of their demography. The present study evaluates the concu rrent influence of age and body mass index (BMI) on GGT in a sample of 133 high functioning young men, with detailed assessment of the patte rn of alcohol use at ages 20 [time 1 (T1)], 30 [time 2 (T2)], and 35 [ time 3 (T3)]. GGT increased between T1 and T2 (15.4 +/- 9.65 units/lit er vs. 20.1 +/- 12.07 units/liter, t = 4.17, p < 0.001), and between T 2 and T3 (20.1 +/- 12.07 units/liter vs. 27.3 +/- 24.69 units/liter, t = 4.11, p < 0.001). Controlling for drinking quantity and frequency d id not change the finding. The relationship between GGT and BMI was es timated after splitting the sample into normal (BMI less than or equal to 25 kg/m(2)) and overweight (BMI > 25 kg/m(2)) subjects. The correl ation between GGT and BMI in normal weight men at T1 was r = 0.15, p = 0.09, at T2 r = 0.00, p = 0.96, and at T3 r = 0.09, p = 0.09. In over weight subjects, correlation at T1 was r = 0.40, p = 0.20, at T2 r = 0 .36, p < 0.05, and at T3 r = 0.44, p < 0.001. Controlling for the effe ct of alcohol consumption and/or age did not alter these conclusions. Testing for the interaction of age, BMI, and alcohol consumption did n ot yield relevant results. We concluded that GGT is positively related to age in the 20s to late 30s and to BMI in overweight subjects; both relationships of age and BMI were independent of alcohol consumption. The interpretation of GGT should take age and BMI into account when s uspecting subclinical alcohol problems in young men.