Gamma GT

GGT (Gamma-Glutamyl Transferase, often shortened to Gamma GT) is a liver enzyme concentrated in the cells lining the bile ducts and, to a lesser extent, throughout the liver itself. Its main role in the body is to help transport amino acids across cell membranes and to support the production of glutathione, one of your body's most important antioxidants. Clinically, GGT is one of the most sensitive markers available for detecting early changes in liver and bile duct health, it often responds to lifestyle pressures well before ALT or AST move.

Picture the bile ducts as a network of drainage pipes carrying bile from the liver down into the digestive tract. The cells lining those pipes are rich in GGT. When the liver or bile ducts are irritated, blocked, or under chemical stress, those cells release GGT into the bloodstream. Because GGT is so easily provoked, it acts like an early-warning light, responsive to things that have not yet done enough damage to trigger the more slowly-moving enzymes. That sensitivity is both its strength (early detection) and its weakness (it can rise for reasons that turn out to be benign).

The factor GGT is most famously sensitive to is alcohol. Even moderate regular drinking can push GGT up, and it typically comes back down within a few weeks of meaningfully reducing intake. This makes GGT a useful and honest feedback signal, and it responds quickly enough that many people find the change encouraging. GGT is also raised by non-alcoholic fatty liver disease (often linked to excess weight, insulin resistance, and a diet high in refined carbohydrates), by bile duct obstruction or inflammation, and by a number of medications, including certain anti-epileptics, some sleep medications, warfarin, and oral contraceptives. Herbal supplements can also be a factor. GGT is almost always interpreted alongside ALP to distinguish liver or bile duct problems from bone problems (GGT is not made by bone), and alongside ALT to work out whether the liver as a whole is inflamed.

If your GGT is raised, your GP will consider the context, your alcohol intake, medications, weight, and other liver markers. Many raised GGT results respond well to specific, achievable lifestyle changes. Where the elevation persists or is significant, further investigation such as a liver ultrasound may be appropriate.