Correlates and reference limits of plasma gamma-glutamyltransferase fractions from the Framingham Heart Study.

BACKGROUND We assessed GGT fractions correlates and their reference values in the Offspring Cohort of the Framingham Heart Study. METHODS Correlates of GGT fractions were assessed by multivariable regression analysis in 3203 individuals [47% men, mean age (SD): 59 (10) years]. GGT fractions reference values were established by empirical quantile analysis in a reference group of 432 healthy subjects [45% men, 57 (10) years]. RESULTS Fractional GGT levels were higher in men than in women (P<0.0001). In both sexes, fractions were associated with: triglycerides were associated with b-GGT, alcohol consumption with m-, s- and f-GGT. C-reactive protein with m- and s-GGT, while plasminogen activator inhibitor-1 with b- and f-GGT. Body mass index, blood pressure, glucose and triglycerides correlated with b- and f-GGT. In comparison with the reference group [b-GGT/s-GGT median (Q1-Q3): 0.51 (0.35-0.79)U/L], subjects affected by cardiovascular disease or diabetes showed no change of b/s ratio [0.52 (0.34-0.79)U/L, 0.57 (0.40-0.83)U/L, respectively]. The b/s ratio was higher in presence of metabolic syndrome [0.61 (0.42-0.87)U/L, P<0.0001], while lower in heavy alcohol consumers [0.41 (0.28-0.64)U/L, P<0.0001]. CONCLUSIONS Metabolic and cardiovascular risk markers are important correlates of GGT fractions, in particular of b-GGT.