Medical Information Only
This site provides general health information for educational purposes only — not a substitute for professional medical advice. Always consult your doctor about your results.
Your LFTs came back abnormal and you've been left with a page of numbers and no explanation. ALT, AST, ALP, GGT, bilirubin, albumin — each tells a different story about your liver. Here's what they mean.
Diagnostic Pathology, Urinalysis ·
The essentials — before you read the full guide below.
ALT and AST measure liver cell damage. ALP and GGT measure bile duct obstruction or infiltration. Bilirubin measures liver filtration. Albumin measures liver synthetic function.
ALT (alanine aminotransferase) is the most liver-specific of the enzymes. Elevated ALT with normal AST and ALP most often indicates mild hepatocellular inflammation — alcohol, fatty liver, or medication-induced.
GGT is highly sensitive to alcohol. Even moderate regular alcohol consumption raises GGT. A GGT elevated out of proportion to ALP suggests alcohol or medication as the cause.
Low albumin does not mean acute liver damage — it indicates the liver has lost synthetic capacity over time. A low albumin in a patient with liver disease suggests advanced cirrhosis or malnutrition.
Reference Ranges
Use the interactive slider below, or read the range cards for a full clinical breakdown.
Drag to see what your Liver Function Tests (LFTs) means
The Science
Liver function tests don't all measure the same thing. The panel divides into two groups: liver damage markers (ALT, AST — released when liver cells die) and cholestasis markers (ALP, GGT — elevated when bile ducts are blocked or infiltrated). Albumin and bilirubin measure what the liver produces and filters — they reflect synthetic and excretory function respectively.
An AST:ALT ratio above 2 is a strong indicator of alcoholic liver disease. In most other liver conditions (NAFLD, viral hepatitis), ALT is higher than AST. In severe acute hepatitis, both may be 10–100× the upper limit of normal.
Elevated ALP with high GGT points to biliary pathology (gallstones, cholangitis, primary biliary cholangitis). Elevated ALP alone (with normal GGT) suggests bone disease — because ALP is also produced by bone, placenta, and intestine.
Albumin takes weeks to fall, so it reflects chronic liver dysfunction rather than acute injury. In acute liver failure, albumin may still be normal despite massive cell death — bilirubin and clotting (PT/INR) are better acute markers.
When to Test
These are the most common reasons a Liver Function Tests (LFTs) test is requested — from symptoms to routine screening.
GGT and ALT are sensitive markers for alcohol-related and non-alcoholic fatty liver disease — the most common cause of mild LFT elevation in western countries.
Most commonStatins, paracetamol/acetaminophen, methotrexate, and many antibiotics can cause drug-induced liver injury (DILI). LFTs are standard monitoring for high-risk drugs.
Drug monitoringVisible jaundice indicates bilirubin above 50 µmol/L. LFTs are essential to determine whether the cause is hepatic (liver damage), prehepatic (haemolysis), or post-hepatic (bile duct obstruction).
Urgent signHepatitis A, B, and C cause marked LFT elevation. LFTs screen for exposure and monitor treatment response. Hepatitis B and C can cause chronic elevation for years.
Hepatitis screeningIntrahepatic cholestasis of pregnancy (ICP) and pre-eclampsia/HELLP syndrome cause characteristic LFT patterns. LFTs are part of obstetric monitoring in complicated pregnancies.
Obstetric monitoringLFTs are commonly included in annual comprehensive blood panels to screen for asymptomatic liver disease.
ScreeningTesting Schedule
Frequency depends on your current health status and your doctor's guidance.
Included in most comprehensive annual panels as part of routine metabolic screening.
Statins, methotrexate, and antiretrovirals require LFT monitoring every 3–6 months. Frequency increases if enzymes rise.
During antiviral treatment for hepatitis B or C, LFTs are monitored monthly to track treatment response.
Established cirrhosis requires bi-annual AFP and LFT monitoring for hepatocellular carcinoma surveillance.
If Your Result Is Abnormal
LFT interpretation is always pattern-based — no single enzyme diagnoses anything alone.
Hepatitis B surface antigen (HBsAg), hepatitis C antibody (anti-HCV), and hepatitis A IgM are the first screen for elevated transaminases without an obvious cause.
Hep B/C serology firstUltrasound of the abdomen is the first-line investigation for cholestatic pattern (elevated ALP + GGT). It detects gallstones, bile duct dilatation, and liver mass.
Liver ultrasoundIsolated GGT elevation (with normal ALP) strongly suggests alcohol or medication. A detailed alcohol history and medication review is essential before further testing.
Alcohol history + drug reviewALT more than 5 times the upper limit of normal (>280 U/L), or any jaundice with elevated enzymes, warrants urgent gastroenterology or hepatology assessment.
Urgent referral thresholdClinician-reviewed articles published in this category — referenced, sourced, and written for patients and practitioners alike.
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Comprehensive guide to liver function test interpretation, explaining LFT results, normal ranges, and what elevated or decreased values mean for health.
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