TUESDAY, Sept. 27, 2005 (HealthDay News) -- An elevated blood level of a molecule produced by liver damage also predicts the risk of heart disease and stroke, an Austrian study finds.
Men with even moderately high levels of the molecule, called gamma-glutamyl transferase (GGT), were at a 28 percent higher risk of dying from cardiovascular disease than those with low levels, researchers report in the Sept. 27 issue of Circulation. For men with the highest levels, the risk was 68 percent greater. In women, the increase in risk ranged from 35 percent to 51 percent, the researchers found.
The study was done as a follow-up to an Italian report linking elevated GGT levels to atherosclerosis, the "hardening of the arteries" that leads to heart disease and stroke, said a statement by study author Hanno Ulmer, an associate professor of medical statistics at the Innsbruck Medical University.
Ulmer and his colleagues used medical data on nearly 164,000 Austrian participants in a long-running health monitoring program. A follow-up of more than 11 years found that an elevated GGT level was a better predictor of cardiovascular death than high levels of blood sugar and cholesterol -- but not as good a predictor as two other major risk factors, smoking and high blood pressure.
A blood test for GGT is widely used to monitor liver function. For example, many doctors give it routinely to people who take cholesterol-lowering statins, where liver damage is a possible side effect. But, Ulmer said, "beyond its role as an indicator of liver function, GGT is very likely to predict cardiovascular disease."
There are two possible reasons why GGT is a marker for cardiovascular disease, Ulmer said. One is that it is an indicator of general damage to the arteries. Alternately, it could indicate the damage done to blood vessels by heavy drinking. The Austrian researchers could not rule out the possibility that heavy drinking was the only cause of elevated levels because they did not have information on alcohol consumption by the study participants.
Further studies are needed to determine the value of GGT testing to assess cardiovascular risk, Ulmer said. It should be "included as a major parameter in future cardiovascular intervention studies," he said.
More studies are necessary, agreed Dr. JoAnn Manson, a professor of medicine at Harvard Medical School and a spokeswoman for the American Heart Association. She said "it isn't clear whether it [GGT level] is an independent indicator if you rule out other biomarkers or cardiovascular risk."
The nature of the Austrian study "makes it difficult to tease out the confounding effect of alcohol consumption," Manson said. "It is an interesting study that warrants confirmation in other populations, especially where you can control for alcohol intake in detail and other biomarkers of risk."
Learn learn more about the GGT test at Lab Tests on Line.