What this test measures
A standard Indian Liver Function Test measures three groups of markers in a single tube of blood. (1) Hepatocellular enzymes — SGPT (ALT) and SGOT (AST) — which leak out of liver cells when they are injured. (2) Cholestatic enzymes — Alkaline Phosphatase (ALP) and GGT — which rise when bile flow is blocked. (3) Synthetic function — Bilirubin (total and direct), Albumin, Globulin, Total Protein, and the A/G ratio — which reflect what the liver is still able to make and clear.
Together these tell you whether the liver is inflamed (high SGPT/SGOT), backed-up (high ALP/bilirubin), or failing to produce essential proteins (low albumin).
Why it matters
Liver disease in India is rising fast — driven by hepatitis B and C, alcohol, and an epidemic of metabolic-associated fatty liver (MAFLD / NAFLD) tied to diabetes and obesity. Most of these conditions are silent for years until they cause cirrhosis or liver failure. An LFT is the cheapest and earliest signal that something is wrong, and is recommended at least annually for anyone with diabetes, obesity, hypertension, regular alcohol use, hepatitis B / C exposure, or on long-term medications metabolised by the liver.
LFTs are also used before starting drugs that can damage the liver (some antibiotics, anti-TB therapy, statins, methotrexate), during pregnancy, and as part of any "what is going on" workup for fatigue, jaundice, itching, abdominal swelling or unexplained weight changes.
How to prepare
Most labs do not require fasting for an LFT, but fasting 8–10 hours is sometimes requested when the LFT is bundled with a Lipid Profile or fasting glucose. Avoid alcohol for at least 24 hours before the test — even a single binge can elevate liver enzymes. Continue your regular medications unless your doctor tells you otherwise, and tell the lab about any drugs (especially paracetamol-containing painkillers and herbal supplements) you have taken in the past week.
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| SGPT (ALT) (U/L)[1][2] | Men < 41 · Women < 33 | Low SGPT is generally not clinically meaningful. | Mild rise (1–3× upper limit) — most often fatty liver, alcohol, hepatitis B/C, drug effect, or muscle source. Significant rise (5–10×) suggests acute hepatitis (viral, drug-induced) and warrants prompt evaluation. Very high (>15×) — acute liver injury, paracetamol toxicity, ischaemic hepatitis, fulminant hepatitis — urgent care needed. |
| SGOT (AST) (U/L) | < 40 | Not clinically significant in isolation. | Often rises with SGPT. An AST/ALT ratio > 2 (with ALT < 300) suggests alcoholic liver disease; ratio < 1 with mild rises suggests fatty liver / chronic hepatitis. Marked isolated AST rise can also reflect heart muscle (recent MI), skeletal muscle injury, or haemolysis — not just liver. |
| Alkaline Phosphatase (ALP) (U/L) | Adults 40–129 | Uncommon — may reflect malnutrition, zinc deficiency, hypothyroidism, or rare genetic disorders. | Cholestasis (bile flow obstruction — gallstones, biliary stricture, primary biliary cholangitis), bone turnover (Paget's disease, healing fracture, vitamin D deficiency in children), pregnancy (placental ALP), or growing adolescents (bone ALP). GGT is high in liver-source ALP rise and normal in bone-source rise. |
| GGT (Gamma Glutamyl Transferase) (U/L) | Men < 60 · Women < 40 | Not clinically meaningful. | Sensitive marker of cholestasis and the most sensitive enzyme for alcohol-related liver injury — often the first enzyme to rise with regular alcohol use. Also rises with biliary disease, drug effect, and fatty liver. |
| Total Bilirubin (mg/dL)[1] | 0.3 – 1.2 | Low bilirubin is not clinically meaningful. | Mild rise (1.2 – 3) — common, often Gilbert's syndrome (a benign genetic variant — indirect bilirubin only). Moderate rise (3 – 10) — viral hepatitis, drug effect, bile duct obstruction. > 10 — significant hepatic dysfunction or biliary obstruction. The split between direct and indirect bilirubin tells you which side of the liver pathway is affected. |
| Albumin (g/dL) | 3.5 – 5.2 | Low albumin signals reduced liver synthesis (chronic liver disease, cirrhosis), nephrotic syndrome (loss in urine), chronic inflammation, malnutrition, or protein-losing enteropathy. Albumin has a 21-day half-life, so it changes slowly — a low value usually means weeks-to-months of stress. | Mild elevation is almost always dehydration, not a true increase in production. |
Patterns of LFT abnormality — and what they suggest
| Pattern | SGPT/SGOT | ALP/GGT | Bilirubin | Typical causes |
|---|---|---|---|---|
| Hepatocellular (acute) | ↑↑↑ (5–50×) | Normal / mild ↑ | Often ↑ | Acute viral hepatitis, drug-induced liver injury, paracetamol overdose, ischaemic hepatitis |
| Hepatocellular (chronic) | ↑ (1–3×) | Normal / mild ↑ | Usually normal | Fatty liver / NAFLD, chronic hepatitis B/C, alcohol, drug effect |
| Cholestatic | Normal / mild ↑ | ↑↑↑ | ↑ (direct fraction) | Bile duct stones, biliary stricture, primary biliary cholangitis, drug cholestasis, pregnancy cholestasis |
| Isolated hyperbilirubinaemia | Normal | Normal | ↑ (indirect) | Gilbert's syndrome (benign), haemolysis, ineffective erythropoiesis |
| Synthetic failure | ↑ or normal | Variable | ↑ | Cirrhosis, fulminant hepatic failure — albumin low, INR high |
Frequently asked questions
Do I need to fast before a Liver Function Test?
Most NABL-accredited Indian labs accept non-fasting LFTs, but a fasting sample is preferred (and required if the LFT is paired with a Lipid Profile or fasting glucose). Avoid alcohol for 24 hours before the test regardless.
My SGPT is 60 — should I be worried?
A mild rise (up to ~3× the upper limit of normal) is very common and most often points to fatty liver, recent alcohol use, certain medications, or muscle source. A single mildly raised value should be repeated after 4–6 weeks with attention to alcohol, weight and meds; if it stays up, your doctor will look at viral hepatitis serology and an abdominal ultrasound.
What is the difference between SGPT and SGOT?
SGPT (ALT) is mostly in the liver — a rise is fairly specific for liver injury. SGOT (AST) is in liver, heart muscle, skeletal muscle and red blood cells — so a rise is less specific. The ratio between them helps point to the cause (AST/ALT > 2 suggests alcoholic liver disease; < 1 suggests fatty liver or chronic hepatitis).
Can fatty liver be detected by LFT alone?
Not reliably. Up to 80% of people with fatty liver have a normal LFT. If fatty liver is suspected (diabetes, obesity, high triglycerides), an abdominal ultrasound or FibroScan is more sensitive — the LFT is a screen, not a confirmatory test.
How often should I get an LFT?
Annually for adults with diabetes, obesity, hypertension, family history of liver disease, regular alcohol use, or known hepatitis B / C. More often if you are on a drug that affects the liver (statins, methotrexate, anti-TB therapy) — your doctor will set the interval.
My bilirubin is high but the other LFT values are normal. What does that mean?
Isolated indirect (unconjugated) bilirubin rise is most often Gilbert's syndrome — a benign genetic variant affecting roughly 5–10% of people. It does not need treatment and bilirubin can rise during fasting, illness or stress. If the direct (conjugated) fraction is also raised, that needs evaluation for bile duct or liver problems.
Will paracetamol affect my LFT?
Therapeutic doses of paracetamol (≤ 3 g/day in healthy adults) usually do not affect liver enzymes. But overdose or chronic high-dose use is the single most common cause of severe drug-induced liver injury. Tell your doctor about all over-the-counter medications and herbal supplements before testing.
What is the role of an LFT in pregnancy?
LFTs are checked in pregnancy if there are symptoms like itching, jaundice, or vomiting. Some pregnancy-specific liver conditions (intrahepatic cholestasis of pregnancy, HELLP syndrome, acute fatty liver of pregnancy) can be serious for both mother and baby. Note that ALP rises normally in late pregnancy due to placental production.
Related Liver / Enzymes tests
Tests commonly ordered alongside Liver Function Test (LFT), or that help interpret an unexpected result.
Sources & references
- AASLD Practice Guidance — Abnormal Liver Chemistries (2017) · accessed 2026-05-29T00:00:00.000Z
- NIH MedlinePlus — Liver Function Tests · accessed 2026-05-29T00:00:00.000Z
- American College of Gastroenterology — Liver Tests · accessed 2026-05-29T00:00:00.000Z
- NCBI StatPearls — Liver Function Tests · accessed 2026-05-29T00:00:00.000Z
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