Measuring gamma-glutamyl transferase (GGT) levels may be a good way to determine whether people have hepatitis C, according to a study reported in the March issue of the Journal of Gastroenterology and Hepatology.

GGT is a protein found in cells that line the bile ducts of the liver.

Researchers at Universidade Federal de Sao Paulo in Brazil measured levels of this protein in 201 patients with chronic hepatitis C. They observed elevated GGT levels in 48 percent of the study participants.

Besides being a sign that someone may have hepatitis C, the researchers also noted that GGT seemed to be useful as an indirect marker of more advanced liver disease in chronic hepatitis C.