The alanine aminotransferase (ALT) blood test measures the levels of the ALT enzyme in the blood. ALT is an enzyme found primarily in the liver, and its levels in the blood can be a marker of liver damage or disease.

The test involves taking a small blood sample and measuring the levels of ALT in the serum. Elevated levels of ALT may indicate liver damage or disease, including hepatitis, cirrhosis, and non-alcoholic fatty liver disease (NAFLD). The test may also be used to monitor the effectiveness of treatment for liver disease.

However, elevated ALT levels can also be caused by other factors, such as alcohol consumption, obesity, certain medications, and muscle damage. Therefore, further testing and evaluation may be necessary to determine the underlying cause of elevated ALT levels.

The ALT blood test is often performed as part of a liver panel, which includes other liver function tests such as aspartate aminotransferase (AST), alkaline phosphatase (ALP), and bilirubin levels. Together, these tests provide a comprehensive evaluation of liver health and function.