I always include GGT (Serum γ-Glutamyltransferase) in our basic screening blood panel, but find often that this is not included in lab work that patients bring from elsewhere. A study recently published in the journal Obesity shows that, besides being associated with fatty liver, GGT is an important metric for predicting metabolic syndrome, diabetes and hypertension. The authors state:
“Serum γ-glutamyltransferase (GGT) is associated with oxidative stress and hepatic steatosis. The extent to which its value in determining incident cardiometabolic risk (coronary heart disease (CHD), metabolic syndrome (MetS), hypertension and type 2 diabetes) is independent of obesity needs to be further explored in ethnicities.”
They examined a cohort of 1,667 adults from a general population age 52 to 63 with 4 year’s follow-up, measuring GGT activity in association with metabolic syndrome (identified by Adult Treatment Panel-III criteria modified for male abdominal obesity) and multiple markers for cardiovascular disease. Their data bolsters the use of GGT for case management:
“Median GGT activity was 24.9 U/l in men, 17.0 U/l in women…while smoking status was not associated, (male) sex, sex-dependent age, alcohol usage, BMI, fasting triglycerides and C-reactive protein (CRP) were significant independent determinants of circulating GGT. Each 1-s.d. increment in (= 0.53 ln GGT) GGT activity significantly predicted in each sex incident hypertension (hazard ratio (HR) 1.20), and similarly MetS, after adjustment for age, alcohol usage, smoking status, BMI and menopause. Strongest independent association existed with diabetes (HR 1.3) whereas GGT activity tended to marginally predict CHD independent of total bilirubin but not of BMI.”
Interestingly…
“Higher serum total bilirubin levels were protective against CHD risk in women.”
While not any stronger a risk predictor for coronary heart disease (CHD) than body mass index (BMI), GTT is a valuable and underutilized marker to use for the case management of cardiometabolic disorders. The authors conclude:
“We conclude that elevated serum GGT confers, additively to BMI, risk of hypertension, MetS, and type 2 diabetes but only mediates adiposity against CHD risk.”