Overview
What are liver function tests?
In Nigeria, a busy teaching hospital recently recorded a surge in routine check-ups where liver panels formed a key part of diagnosis. This isn’t surprising the liver, after all, is a quiet workhorse, performing hundreds of critical tasks from filtering toxins to aiding digestion. Liver function tests, or LFTs, are a group of blood tests designed to measure how well this vital organ is working. They help healthcare professionals detect inflammation, damage, or disease, sometimes long before symptoms appear.
What are the five primary liver function tests?
While “liver function tests” is a broad term, five primary measurements often provide the clearest window into liver health: alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), albumin, and bilirubin. Each plays a distinct role ALT and AST are enzymes that indicate cell injury when elevated, ALP can point to bile duct or bone issues, albumin reflects the liver’s protein-making ability, and bilirubin reveals how well the liver processes waste.
When are tests done to check liver function?
Doctors often order LFTs when patients show symptoms like persistent fatigue, abdominal pain, yellowing of the skin or eyes, or unexplained weight loss. They’re also common in routine health screenings, especially for individuals taking medications that can affect the liver, or those living with chronic conditions such as hepatitis or HIV. In parts of Africa where hepatitis B prevalence is high, these tests can be lifesaving, catching liver injury before it progresses.
What kinds of things can a liver panel tell you?
A well-interpreted liver panel can uncover far more than just “good” or “bad” liver health. It can signal inflammation, pinpoint whether damage is acute or chronic, and even differentiate between problems in the liver itself and issues elsewhere, like the gallbladder or bones. When paired with a patient’s history and imaging studies, LFTs become a powerful decision-making tool.
Test Details
How do liver function tests work?
The principle is straightforward: a small blood sample is analyzed in a lab to measure levels of certain enzymes, proteins, and waste products. Changes in these levels act as signposts, directing clinicians toward possible causes. For example, a sudden spike in ALT might hint at viral hepatitis, while low albumin could suggest long-term liver disease or malnutrition.
What happens during the test?
A healthcare provider cleans the skin, usually in the inner arm, and inserts a needle into a vein to draw a small tube of blood. The process is quick often under five minutes and while there might be mild discomfort, it’s generally minimal. Many patients in busy city hospitals have this done as part of a series of tests in a single sitting, making it efficient and accessible.
What happens after?
Once the sample is taken, results are usually ready within hours to a couple of days. In some urban clinics equipped with in-house labs, same-day results are possible, which can speed up treatment decisions. Patients may be advised to rest, hydrate, or follow specific dietary or medication instructions depending on what the results reveal.
Results and Follow-Up
How do I interpret the results of my liver function test?
Results are best understood in the context of your overall health and medical history. A single abnormal value may not mean disease it could be temporary, linked to diet, exercise, or recent medication use. That’s why follow-up testing is often recommended before drawing conclusions. A trained healthcare professional can piece together the puzzle, looking for trends rather than isolated numbers.
What is the normal range for liver function tests?
While ranges can vary slightly between laboratories, common reference points include ALT between 7–56 units per liter, AST between 10–40, ALP between 44–147, total bilirubin between 0.1–1.2 milligrams per deciliter, and albumin between 3.5–5.0 grams per deciliter. These numbers are a guide, not an absolute verdict.
What do high AST and ALT mean?
High levels of AST and ALT often point to liver cell injury, but they don’t tell the whole story. Elevated enzymes can result from infections like hepatitis, excessive alcohol use, certain medications, or even intense exercise. The ratio between the two enzymes can also guide clinicians toward a more precise diagnosis.
What can a liver function test diagnose?
LFTs can help diagnose hepatitis, cirrhosis, alcoholic liver disease, fatty liver, bile duct obstruction, and even some cancers. However, they’re not stand-alone diagnostic tools. They’re most powerful when used alongside imaging studies, patient history, and sometimes liver biopsies.
Published 29th August 2025
References
Mayo Clinic – Liver function tests – Available at: https://www.mayoclinic.org/tests-procedures/liver-function-tests/about/pac-20394595
Cleveland Clinic – Liver Function Tests – Available at: https://my.clevelandclinic.org/health/diagnostics/17662-liver-function-tests