A liver function test (LFT) is a group of blood tests that checks how well your liver is working. It measures liver enzymes (SGPT/ALT, SGOT/AST, ALP, GGT), bilirubin and proteins such as albumin. An LFT helps detect fatty liver, hepatitis, alcohol-related damage and medicine side effects, often before any symptoms appear.
What does the liver function test measure?
Your liver processes nutrients, filters toxins and medicines, makes proteins and produces bile. When liver cells are stressed or damaged, enzymes leak into the blood and other markers change. An LFT is a panel, so the pattern across values matters more than any single number.
- SGPT (ALT): An enzyme found mainly in the liver. The most specific marker of liver cell injury, and the one most often raised in fatty liver.
- SGOT (AST): Found in the liver, heart and muscles. Read together with SGPT; a higher AST:ALT ratio can point towards alcohol-related injury.
- Alkaline phosphatase (ALP): Raised when bile flow is blocked, and also with bone growth or bone disease.
- GGT: Sensitive to bile duct problems and regular alcohol intake.
- Bilirubin (total, direct, indirect): A yellow pigment from the breakdown of red cells. High levels cause jaundice.
- Total protein, albumin, globulin and A/G ratio: Show how well the liver makes proteins; low albumin can reflect long-term liver disease or poor nutrition.
Fatty liver disease (now often called MASLD) is increasingly common among Indian working adults, linked to weight gain, diabetes and inactivity. It often causes no symptoms, and a mildly raised SGPT on a routine checkup is frequently the first sign.
LFT normal range (adults)
(many labs use up to 45–55 for men)
Women below 40 U/L
Liver enzyme ranges vary more between labs than most tests. Ranges vary between labs and methods. Always compare your result with the reference range printed on your own report.
What abnormal results can mean
- Raised SGPT/SGOT: Can suggest fatty liver, viral hepatitis, alcohol use or a medicine side effect. Strenuous exercise can also raise SGOT briefly.
- Raised ALP and GGT: Can suggest a bile duct blockage, such as gallstones.
- High bilirubin: Can suggest liver disease, bile blockage, or faster breakdown of red cells. Mildly raised indirect bilirubin is often due to Gilbert’s syndrome, a harmless inherited condition.
- Low albumin: Can suggest long-term liver disease, kidney protein loss or poor nutrition.
Mild, isolated changes are common. Your doctor will decide whether a repeat test or ultrasound is needed.
Who should get this test?
- Adults with excess weight, diabetes or high triglycerides, who are at higher risk of fatty liver.
- People who drink alcohol regularly.
- People on long-term medicines that can affect the liver, such as some cholesterol, TB, epilepsy or pain medicines.
- Anyone with symptoms: yellow eyes or skin, dark urine, pale stools, loss of appetite, or pain in the upper right abdomen.
- Preparation: Fasting for 8–12 hours is often advised, especially when an LFT is combined with sugar or lipid tests. Avoid alcohol for 24 hours and heavy exercise the day before.
This page is for general information and is not a substitute for medical advice. Always interpret your results with a qualified doctor.