Alanine Aminotransferase

Alanine aminotransferase (ALT) is an enzyme that is found mainly in the liver but also in the kidney, heart, and skeletal muscle. Under normal conditions, ALT levels in the blood are low. Injury to any of these organs can produce elevations. Damage to the liver is the main cause of an abnormality of this enzyme, but it can be caused by damage to any of the organ systems listed above. ALT is also tested in long-standing liver disease. ALT may be used to monitor the treatment of people who have liver disease or to see if the treatment is working. A large number of medicines may also cause elevations. ALT may be ordered either by itself or along with other tests.


No preparation or fasting is required. A blood sample is taken by a needle from a vein.

  • If you are male, avoid strenuous exercise before the test.

  • Tell the person doing the test if you are a smoker.


  • Adult or child: 0 to 35 units/L (0 to 0.58 microkat/L)

  • Elderly adult may be slightly higher

  • Infant: may be twice as high as an adult

  • Values may be higher in men and African Americans.

Ranges for normal findings may vary among different laboratories and hospitals. You should always check with your caregiver after having lab work or other tests done to discuss the meaning of your test results and whether your values are considered within normal limits.


Your caregiver will go over the test results with you and discuss the importance and meaning of your results, as well as treatment options and the need for additional tests if necessary.


It is your responsibility to obtain your test results. Ask the lab or department performing the test when and how you will get your results.