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Liver function tests

Also called: LFTs, Liver panel, Hepatic function panel, ALT, AST

Liver function tests measure enzymes and proteins that show how healthy your liver is. High liver enzymes are common and often mild.

SampleA small tube of blood from a vein in your arm
Fasting?Sometimes 10 to 12 hours
ResultsUsually 1 day
Good to knowOne result rarely tells the whole story. Your provider looks at your results together with your symptoms, exam, and other tests.

What the test is

ALT and AST rise when liver cells are irritated. Alkaline phosphatase and bilirubin rise with bile flow problems.

What it measures

  • ALT and AST (liver cell enzymes)
  • Alkaline phosphatase and GGT (bile ducts and bone)
  • Bilirubin (yellow pigment)
  • Albumin and total protein (liver making proteins)

Why it's done

  • Monitoring medicines that can affect the liver
  • Symptoms like yellow skin, dark urine, belly pain, or tiredness
  • Heavy drinking, hepatitis, or fatty liver

Getting ready and what happens

  • You may be asked to fast for 10 to 12 hours.

How the test is done

  • A health worker cleans the skin, puts a band around your arm, and draws blood from a vein with a small needle. It takes a few minutes.

What the results mean

ResultTypical range for adults
ALTAbout 7 to 55 U/L (labs vary)
ASTAbout 8 to 48 U/L (labs vary)
Alkaline phosphataseAbout 40 to 130 U/L
Total bilirubinAbout 0.1 to 1.2 mg/dL
Albumin3.5 to 5.0 g/dL

Normal ranges vary from lab to lab and can differ by age, sex, and pregnancy. Your report lists your lab's own range next to each result. A result a little outside the range is often not a problem.

Mildly high ALT and AST

Often from fatty liver, alcohol, medicines (including acetaminophen and statins), or hard exercise. Usually rechecked.

Very high ALT and AST

Can mean hepatitis, a medicine or acetaminophen injury, or poor blood flow to the liver, and needs prompt evaluation.

High alkaline phosphatase or bilirubin

Can point to a blocked bile duct, gallstones, or bone conditions. Mildly high bilirubin alone is often Gilbert syndrome, which is harmless.

When a result needs quick action

Call 911Yellow skin with confusion, vomiting blood, or extreme sleepiness
Call your provider todayNew yellow skin or eyes, dark urine, or pale stool

Questions to ask your provider

  • What do my results mean for me?
  • Do I need to repeat this test or have other tests?
  • What could be raising my liver tests?
  • Should I stop alcohol or any medicines?
  • Do I need hepatitis tests or an ultrasound?

Risks

A blood draw is very safe. You may have slight pain or a small bruise where the needle went in.

Related conditions

Related medicines

Related tests

Sources

Last updated 2026-11-13.