Liver Function Tests: Understanding LFTs and Their Causes

Study Notes

Liver Test Functions

Liver function tests (LFTs) are a group of blood tests that assess the health of your liver. These tests measure the levels of specific enzymes, proteins, and bilirubin in your bloodstream, which can indicate liver damage, inflammation, or impairment.

Enzymes and Proteins

The most common liver function tests include:

Alanine Aminotransferase (ALT): An enzyme found in the liver and heart, high levels of ALT may indicate liver damage or inflammation.
Aspartate Aminotransferase (AST): Another enzyme found in the liver and heart, elevated AST levels can also indicate liver damage or inflammation.
Alkaline Phosphatase (ALP): An enzyme found in the liver and bile ducts, high levels of ALP may suggest liver disease or problems with the bile ducts.
Gamma-glutamyl transferase (GGT): A liver enzyme that breaks down certain amino acids, high levels of GGT can indicate liver damage or inflammation.

Bilirubin

Bilirubin is a yellowish pigment produced when your liver breaks down old red blood cells. High levels of bilirubin can indicate liver problems, such as liver damage or a blockage in the bile ducts.

Albumin

Albumin is a protein produced by the liver. Low levels of albumin can indicate liver problems or an underlying medical condition, such as malnutrition.

Prothrombin Time (PT) and International Normalized Ratio (INR)

These tests measure the clotting ability of your blood. Elevated PT and INR levels can indicate liver problems, such as liver damage or insufficient production of clotting factors.

Other Tests

In some cases, additional tests may be required to further evaluate liver function. These may include:

FibroScan: A non-invasive ultrasound test that measures liver stiffness, which can indicate liver damage or scarring.
Liver biopsy: A procedure in which a small sample of liver tissue is removed for examination. This can provide more detailed information about liver health, including the presence of inflammation, scarring, or other damage.

Causes of Abnormal Liver Test Results

Abnormal liver test results can be caused by various factors, including:

Alcohol consumption: Excessive alcohol consumption can lead to alcoholic liver disease, which can cause elevated liver enzymes and other abnormalities.
Obesity: Non-alcoholic fatty liver disease (NAFLD) is a condition where fat accumulates in the liver, leading to abnormal liver function.
Drugs and medications: Certain medications, such as amiodarone, can cause liver damage and lead to abnormal liver test results.
Viral hepatitis: Viral infections, such as hepatitis A, B, or C, can cause liver damage and result in abnormal liver function tests.
Hepatic inflammation: Conditions like autoimmune hepatitis or drug-induced hepatitis can cause liver inflammation and result in abnormal liver test results.

In summary, liver function tests assess the health of your liver by measuring enzymes, proteins, and bilirubin in your bloodstream. Abnormal results can be caused by various factors, including alcohol consumption, obesity, drugs, and viral hepatitis. Regular monitoring of liver function tests can help identify potential liver problems and guide appropriate treatment.

Description

Learn about liver function tests, including enzymes, proteins, and bilirubin levels, and how they diagnose liver damage, inflammation, or impairment. Discover the causes of abnormal LFT results, such as alcohol consumption, obesity, and viral hepatitis.