Liver Function Tests

Liver Function Tests (LFTs)

Liver Function Tests, also known as LFTs, are tests used to evaluate the health and functioning of the liver. The tests measure the level of certain enzymes and proteins in the blood that are either produced by the liver or affected by the liver.

Preparation for Liver Function Tests

Most lab tests do not require special preparation. It is recommended to fast for 8–12 hours prior to the test. If the liver enzyme test is part of an overall physical, the doctor may require other tests such as a fasting lipid panel, metabolic panel, and hemoglobin A1C.

Procedure for Liver Function Tests

LFTs can be performed by a phlebotomist in a clinic, hospital, or laboratory setting. A blood sample is taken with a needle and placed in a tube. The lab then analyzes the sample for levels of enzymes or proteins that can indicate problems with the liver, such as hepatitis or cirrhosis.

Types of Liver Function Tests

  • Alkaline Phosphatase (ALP)
  • Alanine Transaminase (ALT)
  • Aspartate Transaminase (AST)
  • Gamma-Glutamyl Transpeptidase (GGT)
  • Bilirubin
  • Albumin
  • Total Protein
  • Prothrombin Time (PT) and International Normalized Ratio (INR)

Risks of Liver Function Tests

There are very few risks associated with LFTs. As with any blood test, there is a small risk of infection, bleeding, bruising, and discomfort associated with the needles used to draw the blood sample.

Why are Liver Function Tests Needed?

Liver Function Tests are used to monitor and diagnose diseases and conditions of the liver. These tests can identify liver disease, monitor the effects of medications and treatment plans, and detect damage from toxins including alcohol, drugs, or poisonous chemicals.

When are Liver Function Tests Needed?

Liver Function Tests are part of routine screenings in certain populations, like pregnant women or those who have certain chronic diseases. They may also be ordered when someone has symptoms that suggest liver disease or damage, such as jaundice, abdominal pain, or fatigue.