Liver Function Tests (ALT, AST, GGT, ALP)
The liver processes nutrients, makes proteins, breaks down medicines and clears waste products such as bilirubin. Liver function tests are a group of blood tests that show whether liver cells are damaged or whether the flow of bile is blocked. They are often abnormal before any symptoms, such as jaundice, appear.
At YGOPH, these tests are used to follow women with hepatitis B, to detect serious pregnancy complications such as HELLP syndrome and cholestasis of pregnancy, and to monitor patients taking medicines that can affect the liver, including some treatments for tuberculosis, HIV and epilepsy. In newborns with jaundice, bilirubin is measured to decide on treatment.
What do liver function tests measure?
ALT and AST are enzymes found inside liver cells; they leak into the blood when the cells are damaged, for example by viral hepatitis or medicines. GGT and alkaline phosphatase (ALP) rise mainly when the flow of bile is disturbed. Bilirubin, the yellow pigment responsible for jaundice, and albumin, a protein made by the liver, complete the picture. Your doctor chooses the tests according to the question.
- Jaundice, dark urine, pale stools or itching
- Follow-up of hepatitis B or C
- Pregnant women with high blood pressure, upper abdominal pain or severe itching
- Monitoring of medicines that can affect the liver
- Jaundice in a newborn baby
Good to know
Liver tests in pregnancy
Alkaline phosphatase naturally rises in the second half of pregnancy because the placenta also produces it, so a high ALP alone is usually not worrying. By contrast, raised ALT and AST in a woman with pre-eclampsia may indicate HELLP syndrome, which needs urgent care. Intense itching of the palms and soles in late pregnancy can be a sign of cholestasis.
Newborn jaundice
Many newborns become slightly yellow in their first week, and this usually clears on its own. When jaundice appears in the first 24 hours, is intense or lasts beyond two weeks, bilirubin is measured to decide whether phototherapy or other treatment is needed. Ask the laboratory about the price of bilirubin tests.
Understanding your results
A mild rise in liver enzymes is common and can be temporary, for example after an infection. Large rises or a persistent pattern need investigation. Results are always interpreted with your symptoms and other tests, such as hepatitis serology, ultrasound and the prothrombin time.