Introduction
Liver function tests are usually a group of blood tests—ALT, AST, ALP, bilirubin, albumin, and sometimes GGT or total protein. They help assess the liver and bile ducts.
Despite the name "function," many markers reflect cell injury or bile blockage rather than full organ capacity. Ranges vary by lab; doctors interpret results with symptoms and imaging.
Why this test is done
Liver Function Tests (LFT Panel) is commonly considered in situations such as:
- Jaundice, fatigue, nausea, or abdominal discomfort
- Monitoring medicines, alcohol use, or viral hepatitis risk
- Baseline before surgery or new treatments
- Follow-up of known liver disease
- Unexplained itching or weight loss as part of evaluation
How the test is done
- Blood is drawn from a vein.
- The lab reports multiple markers on one panel.
- Hepatitis serology or ultrasound may be added.
- Trends over time often matter more than a single report.
Preparation and precautions
- Many centers request 8–12 hours fasting—confirm instructions.
- You may be asked to avoid alcohol and herbal products beforehand.
- Provide a full prescription and over-the-counter medicine list.
- Report pregnancy and recent severe illness.
Understanding results
Your clinician interprets lab or imaging ranges together with your symptoms. Online “normal values” do not always apply to your case.
- Raised ALT/AST may suggest hepatocellular injury pattern.
- Raised ALP/bilirubin may point toward cholestasis or blockage.
- Albumin and INR (separate test) give clues about longer-term function.
- Online "normal" ranges may not match your laboratory.
- Medicine changes are made only by your clinician.
Risks or limitations
- Minor discomfort at the blood draw site.
- Confusion from wrong preparation or lab variation.
- Anxiety or self-medication based on numbers alone.
After the test
- Review the report with your doctor.
- Repeat tests or imaging may be scheduled.
- Go to hospital for severe pain, black stools, vomiting blood, or confusion.
Frequently asked questions
If LFTs are normal, is my liver definitely healthy?
Often reassuring, but some diseases can be missed. Persistent symptoms may need more testing.
Are LFTs always abnormal in fatty liver?
No. Enzymes can be normal; imaging and metabolic risk factors are assessed separately.
How often should LFTs be repeated?
Your doctor sets intervals based on cause and treatment plan.
Important caution
This article is general health information. It is not personal medical advice or a prescription.
Your clinician decides whether you need this test, how to prepare, and what the results mean. If you have emergency symptoms, go to hospital without waiting for a lab report.