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Alanine Aminotransferase (ALT)

Risks

There is very little chance of a problem from having blood sample taken from a vein.

  • You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes.
  • In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. A warm compress can be used several times a day to treat this.
  • Ongoing bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medicines can make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medicines, tell your doctor before your blood sample is taken.

Results

An alanine aminotransferase (ALT) test measures the amount of this enzyme in the blood. Results are usually available within 12 hours.

Normal

The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

Alanine aminotransferase 1

Males:

10–40 units per liter (U/L) or 0.17–0.68 microkats per liter (mckat/L)

Females:

7–35 U/L or 0.12–0.60 mckat/L

High values

High levels of ALT may be caused by:

  • Liver damage from conditions such as hepatitis or cirrhosis.
  • Lead poisoning.
  • Exposure to carbon tetrachloride.
  • Decay of a large tumor (necrosis).
  • Many medicines, such as statins, antibiotics, chemotherapy, aspirin, narcotics, and barbiturates.
  • Mononucleosis.
  • Growth spurts, especially in young children. Rapid growth can cause mildly elevated levels of ALT.

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

  • Taking medicines. Talk with your doctor about all the prescription and nonprescription medicines you are taking. You may be instructed to stop taking your medicines for several days before the test.
  • Taking some herbs and natural products, such as echinacea and valerian.
  • Strenuous exercise, injury to a muscle, or injections into a muscle.
  • Recent cardiac catheterization or surgery.

What To Think About

  • The alanine aminotransferase (ALT) value is often used along with the results of the aspartate aminotransferase (AST) test to obtain the AST to ALT ratio. This value can often help determine whether there is damage to the liver related to alcohol abuse. For more information, see the topic Aspartate Aminotransferase (AST).
  • In children with acute lymphocytic leukemia (ALL), very high ALT levels may mean that the disease is likely to progress rapidly.
  • Many different conditions can raise ALT blood levels, so other testing is usually needed to interpret an abnormal ALT result.

WebMD Medical Reference from Healthwise

Last Updated: November 04, 2011
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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