Gamma-glutamyl transferase (GGT)
Chemistry ·Also called: GGT, gamma GT, gamma-glutamyl transpeptidase
What it is
GGT is bound to the membranes of bile duct cells and, to a lesser extent, other tissues. Damage or pressure on the biliary system releases it into the blood, which makes it a more targeted marker of bile trouble than ALP.
Why your vet measures it
In cats especially, the ALP-to-GGT relationship is a diagnostic shortcut. Hepatic lipidosis typically raises ALP sharply with GGT staying near normal, while inflammation of the bile ducts raises GGT more than ALP. That distinction changes the treatment plan.
What a high result can mean
- Obstruction or inflammation of the bile ducts
- Cholangitis in cats, or gallbladder disease in dogs
- Steroid treatment and Cushing's disease in dogs
- Pancreatitis compressing the bile duct
- Newborn puppies and kittens, which have very high GGT from colostrum in the first days of life
What a low result can mean
- Not clinically significant
Dogs and cats differ
The ALP-high, GGT-normal pattern in a cat that has been off its food strongly suggests hepatic lipidosis. A cat with both raised points more towards cholangitis. Dogs do not show this split as cleanly, and canine GGT usually just tracks ALP upwards.
Questions worth asking your vet
- How do the ALP and GGT compare, and what does the pattern point to?
- Do we need imaging of the gallbladder and bile ducts?
Related terms
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