How is it used?
When is it requested?
A doctor usually requests an ALT test with other laboratory investigations to evaluate a patient who is at risk of or has of a liver disorder. Some of these symptoms include , dark urine, nausea, vomiting, abdominal swelling, unusual weight gain and abdominal pain. ALT can also be used, either by itself or with other tests, for:
- persons who have a history of known or possible exposure to hepatitis
- those who drink too much alcohol,
- those whose family have a history of liver disease,
- people who take drugs that might damage the liver.
In people with mild symptoms, such as tiredness or loss of energy, ALT may be tested to make sure they do not have chronic (long-term) liver disease. ALT is often used to monitor the treatment of persons who have liver disease, to see if the treatment is working, and may be ordered either by itself or along with other tests.
What does the test result mean?
Very high levels of ALT (more than 10 times the highest normal level) are usually due to (short-term) hepatitis, often due to a . In acute hepatitis, ALT levels usually stay high for about 1–2 months, but can take as long as 3–6 months to return to normal.
ALT levels are usually not as high in hepatitis, often less than 4 times the highest normal level: in this case, ALT levels often vary between normal and slightly increased, so doctors will order the test frequently to see if there is a pattern. In some liver diseases, especially when the ducts are blocked, or when a person has , ALT may be close to normal levels.
Male 5 - 40 U/L
Female 5 - 35 U/L
The reference intervals shown above are known as a harmonised reference interval. This means that eventually all laboratories in Australia will eventually use this same interval so wherever your sample is tested, the reference interval should be the one shown above. Laboratories are in the process of adopting these harmonised intervals so it is possible that the intervals shown on the report of your results for this test may be slightly different until this change is fully adopted. More information can be found under Reference Intervals – An Overview.
Is there anything else I should know?
Certain drugs may raise ALT levels by causing liver damage in a very small percentage of patients taking the drug. This is true of both prescription drugs and some ‘natural’ health products. If your doctor finds that you have a high ALT, tell him or her about all the drugs and health products you are taking.