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Liver Test

Liver Function Test (LFT)

LFT checks how well your liver is working by measuring enzymes and proteins it produces. Here's what every value in your report means.

Written and clinically reviewed by Suman Konda, PharmD, Clinical Pharmacist · Based on peer-reviewed sources · Editorial policy · Not medical advice

Last reviewed and updated: · How we check our content

What is an LFT test?

A Liver Function Test (LFT) is a group of blood tests that measure different enzymes, proteins and substances produced by your liver. The liver performs over 500 functions including filtering toxins, producing proteins, and aiding digestion. LFT helps doctors detect liver damage, inflammation, fatty liver, hepatitis and other liver conditions early.

LFT Normal Range Chart

TestNormal RangeUnit
SGOT (AST)10 – 40U/L
SGPT (ALT)7 – 56U/L
Alkaline Phosphatase (ALP)44 – 147U/L
Total Bilirubin0.1 – 1.2mg/dL
Direct Bilirubin0.0 – 0.3mg/dL
Indirect Bilirubin0.1 – 1.0mg/dL
Total Protein6.0 – 8.3g/dL
Albumin3.5 – 5.0g/dL
Globulin2.0 – 3.5g/dL
GGT8 – 61U/L

What does high SGPT (ALT) mean?

HIGH SGPT above 56 U/L

SGPT is the most specific marker of liver cell damage. High SGPT means liver cells are injured and leaking this enzyme into the blood. Common causes include fatty liver disease (NAFLD), alcohol use, hepatitis B or C, certain medications (paracetamol overuse, TB drugs), and obesity. Mildly high SGPT (up to 3x normal) is common with fatty liver.

What does high SGOT (AST) mean?

HIGH SGOT above 40 U/L

SGOT can be elevated due to liver damage but also from heart muscle damage, strenuous exercise, or muscle injury. When both SGOT and SGPT are high together, it strongly suggests liver disease. If SGOT is much higher than SGPT, alcohol-related liver disease or heart attack may be the cause.

What does high bilirubin mean?

HIGH Total Bilirubin above 1.2 mg/dL

High bilirubin causes jaundice: yellowing of skin and eyes. Causes include liver disease, bile duct blockage, or excessive breakdown of red blood cells (haemolysis). In newborns, high bilirubin (neonatal jaundice) is common and usually treated with phototherapy. High direct bilirubin suggests liver or bile duct problem; high indirect suggests red cell breakdown.

What does low albumin mean?

LOW Albumin below 3.5 g/dL

Low albumin indicates the liver is not making enough protein: this happens in chronic liver disease, cirrhosis, malnutrition or kidney disease (where albumin leaks into urine). Low albumin causes fluid to accumulate in legs and abdomen (oedema and ascites).

Fatty liver and LFT

Fatty liver disease (now usually called MASLD) is the commonest liver abnormality in most countries, driven by excess weight, insulin resistance and inactivity. Fatty liver typically causes mildly raised SGPT (40–120 U/L) with normal bilirubin and albumin. It is reversible with diet changes and weight loss in early stages.

What each liver test tells you

Liver function tests are a panel rather than a single measure. ALT and AST are enzymes released when liver cells are injured, so they rise in conditions like fatty liver, hepatitis and alcohol-related damage. ALP and GGT relate more to the bile ducts, rising when bile flow is obstructed. Bilirubin reflects the liver's ability to process the breakdown product of red cells, and albumin plus clotting reflect how well the liver is synthesising proteins.

Reading the pattern is what matters: a predominantly ALT/AST rise points to liver-cell injury, while a predominantly ALP/GGT rise points to a bile-duct or 'cholestatic' problem.

Common reasons for abnormal liver tests

The most common cause of mildly raised liver enzymes today is non-alcoholic fatty liver disease, linked to weight, diabetes and metabolic health. Other causes include alcohol, viral hepatitis, medication effects (including some common painkillers and cholesterol drugs), and gallstones.

Mildly abnormal results are frequently temporary and benign, which is why they are often simply repeated after a few weeks before any further investigation.

What happens after an abnormal result

If liver tests stay abnormal, the next steps usually include a review of alcohol and medication, blood tests for viral hepatitis and other causes, and an ultrasound scan of the liver. The degree and pattern of abnormality guide how urgently this is pursued.

Reassuringly, most people with mild elevations do not have serious liver disease: but persistent or marked abnormalities always deserve proper assessment.

Frequently Asked Questions

Do I need to fast for liver function tests?
Fasting is not usually required for LFTs, though they are sometimes taken alongside fasting tests such as glucose or lipids.
Can medicines cause abnormal liver tests?
Yes. Many medicines, including some painkillers, statins and antibiotics, can raise liver enzymes. Always tell your doctor everything you take, including supplements.
Does a raised ALT mean liver damage?
A raised ALT indicates liver-cell irritation or injury, but this is often mild and reversible, such as in fatty liver. The level, trend and other tests determine how significant it is.
Can exercise affect liver test results?
Yes. Strenuous exercise can transiently raise AST (which is also found in muscle), which is one reason results are interpreted in context and sometimes repeated.

Why your lab's "normal" ALT may be too generous

Most laboratories still report an ALT upper limit of around 40–56 U/L. That figure originates from older reference populations that unknowingly included people with undiagnosed fatty liver and hepatitis, which pushed the "normal" ceiling upwards.

A landmark study of 6,835 healthy blood donors (Prati and colleagues, Annals of Internal Medicine, 2002) recalculated healthy limits after excluding people with any risk factor for liver disease. The updated thresholds were substantially lower: and sex-specific:

SourceUpper limit: MenUpper limit: Women
Traditional laboratory range40 U/L30 U/L
Updated healthy range (Prati 2002)30 U/L19 U/L

Using the lower limits raised sensitivity for detecting genuine liver injury from 55% to 76%. The practical implication is important: an ALT of 35 U/L may be flagged "normal" by your laboratory, yet still warrant attention, particularly if you have obesity, type 2 diabetes, raised triglycerides or drink alcohol regularly, since these are the strongest predictors of a raised ALT in otherwise healthy people.

What to do with thisDo not treat a "normal" ALT as a clean bill of liver health if you carry metabolic risk factors. Equally, a mildly raised ALT is common and usually reflects fatty liver rather than serious disease. It is a prompt for review, not alarm.

References

The clinical information on this page is based on peer-reviewed sources indexed in PubMed, the biomedical literature database of the US National Library of Medicine.

  1. Prati D, Taioli E, Zanella A, et al. Updated definitions of healthy ranges for serum alanine aminotransferase levels. Ann Intern Med. 2002;137(1):1-10. doi:10.7326/0003-4819-137-1-200207020-00006 · PMID 12093239
  2. England K, Thorne C, Pembrey L, Tovo PA, Newell ML. Age- and sex-related reference ranges of alanine aminotransferase levels in children. J Pediatr Gastroenterol Nutr. 2009;49(1):71-7. doi:10.1097/MPG.0b013e31818fc63b · PMID 19465871
  3. Liver Function Tests. In: StatPearls. Treasure Island (FL): StatPearls Publishing. NCBI Bookshelf NBK482489

Related reading

Medical Disclaimer: LFT reference ranges may vary between laboratories. A single abnormal result does not necessarily mean serious liver disease. This information is for educational purposes only and does not replace medical advice. Always consult your doctor about your liver function test results.