Liver function tests are a group of blood tests. Some show whether liver cells are irritated or damaged (the enzymes), and others show how well the liver is doing its work (bilirubin, albumin).

Slightly raised results are common and often go back to normal. The pattern across the tests, and how it changes over time, tells a doctor more than one number.

Every lab sets its own normal range, based on its equipment and the people it tests. Always compare your result with the range printed on your own report.

Why this test is done

Routine check, or when taking medicines that can affect the liver
Alcohol use, fatty liver or hepatitis
Yellow skin or eyes, dark urine, belly pain

What each result means

ALT(alanine aminotransferase, SGPT)

An enzyme mainly found in the liver.

Typical adult range: About 7 to 55 U/L (labs differ; some use lower upper limits).

If high: Points to liver cell irritation. Common causes are fatty liver, alcohol, some medicines and viral hepatitis.

AST(aspartate aminotransferase, SGOT)

An enzyme in the liver, and also in muscle and the heart.

Typical adult range: About 8 to 48 U/L.

If high: Can come from the liver or from muscle, for example after hard exercise.

ALP(alkaline phosphatase)

An enzyme in the bile ducts and in bone.

Typical adult range: About 40 to 130 U/L in adults; higher in children, teenagers and pregnancy.

If high: Can point to a blocked bile flow or to bone growth or bone disease.

GGT(gamma-glutamyl transferase)

An enzyme that helps show whether a high ALP comes from the liver.

Typical adult range: About 8 to 61 U/L.

If high: Often raised with alcohol, fatty liver, bile duct problems and some medicines.

Bilirubin

A yellow substance made when old red cells are broken down; the liver clears it.

Typical adult range: Total about 0.1 to 1.2 mg/dL (about 2 to 21 umol/L).

If high: Can cause yellow skin or eyes. Mild, harmless rises are common with Gilbert's syndrome.

Albumin

The main protein the liver makes.

Typical adult range: About 3.5 to 5.0 g/dL (35 to 50 g/L).

If low: Can be low with long-term liver disease, kidney disease, poor nutrition or serious illness.

Before the test

Usually no fasting. Tell your doctor about all medicines and supplements, including herbal ones.
Hard exercise in the days before can raise AST and ALT.

Questions to ask your doctor

Which results are raised, and by how much?
Does the pattern point to the liver cells, the bile ducts or something else?
Should I repeat the test or have a scan?
Could alcohol, weight, or a medicine I take be the cause?

When to get help fast: Get medical help quickly for yellow skin or eyes with fever or confusion, vomiting blood, black stools, or severe belly pain. In an emergency, call your local emergency number.

Sources

This guide is general information written in plain words. It is not medical advice and has not been reviewed by a doctor for your situation. Read our medical disclaimer.

Liver function tests (LFTs): ALT, AST, ALP and bilirubin explained