The Tromsø Heart Study: distribution of, and determinants for, gamma-glutamyltransferase in a free-living population.

Gamma-glutamyltransferase (GGT) was measured in 1579 men, aged 20-54 years, and 1654 women, aged 20-49 years, screened for coronary risk factors. The distribution was right-skewed with medians 15 and 10 U/l for men and women, respectively. Less than 3.8% of the men and 0.8% of the women had GGT greater than or equal to 50 U/l. The low level of GGT matched well with the low mortality of cirrhosis and the modest use of alcohol in Norway. Multiple regression analysis for each sex showed a strong positive association with body mass index, use of alcohol and, unexpectedly, a negative association with coffee consumption, whereas serum triglycerides and the time since the last meal showed a weaker positive association. In women, use of oral contraceptives was positively associated with GGT.