Liver Function Test (LFT)

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 Ranges

What does high SGPT (ALT) mean?

What does high SGOT (AST) mean?

What does high bilirubin mean?

What does low albumin mean?

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: in a study that tracked biopsy changes over a year of lifestyle intervention, people who lost at least 10% of their body weight saw steatohepatitis resolve in 90% of cases and early scarring (fibrosis) actually regress in 45%, while smaller weight losses of 5–10% still helped, just less consistently.³

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.

ALT vs AST vs ALP vs bilirubin vs albumin: how they compare

The LFT panel mixes injury markers, cholestasis markers and function markers — they are not interchangeable:

Injury (ALT/AST) versus cholestasis (ALP/bilirubin) versus function (albumin) — the pattern across the three groups is the diagnosis.

Reading your report: what your doctor actually looks at

When a doctor opens an LFT, no single line stands alone. Here is the checklist they run through — and the same checklist helps you read your own report calmly:

1. How high is the ALT? Slightly raised ALT with everything else normal is the commonest abnormal LFT — and often transient (exercise, a heavy meal, minor illness). The size of the rise matters more than the flag.
2. What is the pattern? ALT-dominant suggests hepatocellular injury; ALP/bilirubin-dominant suggests cholestasis — different patterns, different workups.
3. What medicines are on board? Paracetamol in excess, statins, antibiotics, anti-TB drugs, herbal products — drug-induced liver injury is common and often reversible. The medication list is half the interpretation.
4. Could it be fatty liver? Mild ALT elevation with metabolic risk factors is fatty liver until shown otherwise — ultrasound and lifestyle assessment follow.
5. Isolated bilirubin? High bilirubin with normal enzymes is often Gilbert's syndrome — a benign inherited trait, not liver disease — or haemolysis. The enzymes arbitrate. Discuss the full picture with your doctor.

Most mildly abnormal LFTs are transient or explainable — medicines, exercise, fatty liver — and the first step is usually a careful repeat, not a scan. Discuss the full picture with your doctor.

LFT test price in India: typical bands across major lab chains

The LFT is a bundled panel everywhere — standalone liver enzymes are rarely ordered. Typical list-price bands for the panel:

These are approximate bands, not quotes: prices change often and vary by city, and home collection can add a small fee. Because it is a specialised test, smaller centres may send the sample to a reference laboratory, which can add a day to the result. Where possible, choose a NABL-accredited lab.

Frequently Asked Questions

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.² The updated thresholds were substantially lower: and sex-specific:

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.

Pharmacist's practical notes

Medicines lead the differential for new LFT abnormalities: paracetamol above recommended doses, statins, anti-TB drugs, some antibiotics and herbal products all move these enzymes — and the injury is often reversible on stopping. A new abnormal LFT deserves a medication and supplement review before any scan.

Don't stop prescribed medicines over a mild enzyme rise without medical advice — the risk-benefit needs a doctor's eye, especially for anti-TB treatment where stopping is dangerous. And declare every herbal and ayurvedic product: “natural” doesn't mean liver-safe.

In India

The LFT test typically costs &rupee;500–&rupee;1,000 in India, though prices vary by city and lab.

Where possible, choose a NABL-accredited lab. Fatty liver is increasingly common — mild ALT elevation with metabolic risk factors usually starts with lifestyle assessment, not alarm.

References

Sources cited on this page. PubMed links open the original abstract.

1. Pratt DS, Kaplan MM. Evaluation of abnormal liver-enzyme results in asymptomatic patients. N Engl J Med. 2000;342(17):1266–1271. PMID 10781624 · doi:10.1056/NEJM200004273421707
2. 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. PMID 12093239 · doi:10.7326/0003-4819-137-1-200207020-00006
3. Vilar-Gomez E, Martinez-Perez Y, Calzadilla-Bertot L, et al. Weight Loss Through Lifestyle Modification Significantly Reduces Features of Nonalcoholic Steatohepatitis. Gastroenterology. 2015;149(2):367–378. PMID 25865049 · doi:10.1053/j.gastro.2015.04.005