What does an ALT lab test screen for?

The ALT lab test, also known as the alanine aminotransferase test, is used to measure the levels of the enzyme alanine aminotransferase (ALT) in the blood. ALT is an enzyme that is found in the liver cells, and when the liver is damaged, ALT is released into the bloodstream. Therefore, an ALT test is used to assess liver function and to screen for liver damage or disease.

High ALT levels can indicate liver damage or inflammation caused by various conditions, including:

1. Acute Hepatitis: ALT levels can be significantly elevated in viral hepatitis infections such as hepatitis A, B, and C.

2. Chronic Hepatitis: Elevated ALT levels may be observed in chronic liver inflammation, including chronic hepatitis B and C.

3. Alcoholic Liver Disease: Excessive alcohol consumption can lead to liver damage, and chronic alcohol abuse can cause elevated ALT levels.

4. Non-Alcoholic Fatty Liver Disease (NAFLD): This condition involves the accumulation of fat in the liver, and can lead to elevated ALT levels.

5. Liver Cirrhosis: Cirrhosis is characterized by the scarring and damage of liver tissue, and it can cause persistently high ALT levels.

6. Liver Cancer: Elevated ALT levels may be seen in individuals with primary liver cancer or metastatic liver involvement.

7. Medications and Toxins: Certain medications and toxic substances can cause liver damage and lead to elevated ALT levels.

8. Autoimmune Hepatitis: It is an autoimmune disorder that causes liver inflammation, resulting in increased ALT levels.

It's important to note that slightly elevated ALT levels do not always indicate a serious liver condition, and further tests and evaluations may be necessary to determine the cause of the elevation. Additionally, ALT levels alone cannot provide a complete diagnosis, and a combination of tests, including other liver enzyme markers, imaging studies, and medical history, is typically used for accurate diagnosis.