Overview on Alanine Aminotransferase (ALT) – (SGPT)

A physician usually orders an ALT test (and several others) to evaluate a patient who has symptoms of a liver disorder. Some of these symptoms include jaundice, dark urine, nausea, vomiting, abdominal swelling, unusual weight gain, and abdominal pain. ALT can also be ordered, either by itself or with other tests, for: 

  • persons who have a history of known or possible exposure to hepatitis viruses
  • those who drink too much alcohol
  • individuals whose families have a history of liver disease, or persons who take drugs that might occasionally damage the liver.

In persons with mild symptoms, such as fatigue or loss of energy, ALT may be tested to make sure they do not have chronic 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.

Very high levels of ALT (more than 10 times the highest normal level) are usually due to acute hepatitis, often due to a virus infection. In acute hepatitis, ALT levels usually stay high for about 1–2 months, but can take as long as 3–6 months to come back to normal.

ALT levels are usually not as high in chronic hepatitis, often less than 4 times the highest normal level: in this case, ALT levels often vary between normal and slightly increased, so doctors typically will order the test frequently to see if there is a pattern. In some liver diseases, especially when the bile ducts are blocked, when a person has cirrhosis, and when other types of liver cancer are present, ALT may be close to normal levels.

Test: Alanine aminotransferase (ALT)
Specimen Required: Serum (clotted blood)
When Tested: Daily
Classification: Liver Function Tests
Reference Ranges: <50 Units U/L

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