Seven-year longitudinal population study of change in gamma-glutamyltransferase: the Tromsø Study.

The determinants of individuals changes in gamma-glutamyltransferase (GGT) were examined in 1,171 males and 1,267 females in Tromsø, Norway, according to a 7-year longitudinal design. The basis for the study was two comprehensive population surveys in 1979-1980 and 1986-1987. In both sexes, increase in GGT displayed a strong association with increase in body mass index and hours fasting. In males, increase in GGT also showed a strong association with increase in frequency of inebriation and with decrease in physical activity. In females, increased systolic blood pressure, starting to use oral contraceptives, the occurrence of menopause, and decrease in consumption of boiled coffee were associated with increase in enzyme levels. The strengths of the associations were considerably greater in this longitudinal design compared with earlier cross-sectional studies.