Liver Function Test (LFT): SGOT, SGPT, Bilirubin and Normal Values Explained

A liver function test (LFT) is a blood panel that measures enzymes and proteins made by or released from the liver. SGOT (now called AST) and SGPT (ALT) are enzymes that leak into the blood when liver cells are injured. Normal values are roughly up to 40 U/L for both, though ranges differ by lab. Total bilirubin is normally about 0.3 to 1.2 mg/dL, with direct bilirubin up to about 0.3 mg/dL. Which tests are raised, and by how much, tells doctors whether the problem is liver cell damage, a blocked bile duct or a failing liver, and it is the pattern that matters more than any single number.

This guide explains each line on the report, typical normal ranges, how to recognise the main patterns, a simple calculation doctors use, the common causes in India and the steps to take if your results are abnormal.

What the liver does, and why testing it helps

The liver processes nutrients, makes proteins (including albumin and clotting factors), produces bile to digest fat, clears bilirubin (a waste product from old red blood cells), and breaks down drugs and toxins. Because the liver has large reserves, disease can be silent for years. A blood test is often the first clue.

"LFT" is a bit of a misnomer. Many of the tests show liver injury rather than true "function". Albumin, bilirubin and clotting tests are the real function markers.

The tests and normal ranges

Reference ranges differ between laboratories and by age and sex. Always compare with the range printed on your report. Typical adult values:

| Test | Typical range | Also called | |---|---|---| | ALT (alanine aminotransferase) | About 7 to 40 U/L (some labs: up to 35 in women, 45 to 56 in men) | SGPT | | AST (aspartate aminotransferase) | About 10 to 40 U/L | SGOT | | ALP (alkaline phosphatase) | About 44 to 147 U/L in adults (higher in children, adolescents and pregnancy) | | | GGT (gamma-glutamyl transferase) | About 8 to 61 U/L (varies by sex) | | | Total bilirubin | About 0.3 to 1.2 mg/dL | | | Direct (conjugated) bilirubin | About 0 to 0.3 mg/dL | | | Indirect bilirubin | Total minus direct; about 0.2 to 0.9 mg/dL | | | Total protein | About 6.0 to 8.3 g/dL | | | Albumin | About 3.5 to 5.0 g/dL | | | Globulin | About 2.0 to 3.5 g/dL | | | A/G ratio | About 1.0 to 2.2 | | | PT/INR (separate test) | INR about 0.8 to 1.2 | |

What each one means

SGOT (AST). Found in the liver, but also in heart, muscle and kidney. A raised AST can come from the liver or from muscle injury (hard exercise, injury, a heart attack).

SGPT (ALT). More specific to the liver. A raised ALT is the more reliable sign of liver cell injury.

ALP. Found in bile ducts and in bone. Raised in bile duct blockage, gallstones, some liver diseases, bone growth, healing fractures and pregnancy.

GGT. Raised in bile duct disease and with alcohol or certain medicines. Helps tell whether a high ALP comes from the liver (GGT also high) or from bone (GGT normal).

Bilirubin. Total bilirubin is split into indirect (unconjugated, before processing by the liver) and direct (conjugated, after). High indirect bilirubin suggests excess red cell breakdown or reduced liver uptake, as in haemolysis or Gilbert's syndrome. High direct bilirubin suggests the liver cannot excrete bilirubin into bile, as in hepatitis, cirrhosis or bile duct obstruction. Jaundice (yellow skin and eyes) usually becomes visible when total bilirubin rises above about 2.5 to 3 mg/dL.

Albumin and total protein. Low albumin shows that the liver is making less protein over a longer time (weeks), as in chronic liver disease and cirrhosis, but also in kidney disease (protein loss in urine), malnutrition and chronic illness.

PT/INR. Reflects the liver's ability to make clotting factors. A prolonged INR in liver disease means significant loss of function (after vitamin K deficiency is excluded).

Patterns: what the numbers suggest

Hepatocellular pattern (liver cell injury)

ALT and AST are raised out of proportion to ALP.

• Mild rise (under about 3 times the upper limit): fatty liver (the commonest cause), medicines, early viral or alcohol-related disease, muscle conditions.
• Moderate to marked rise (5 to 10 times or more): acute viral hepatitis (A, B, E, sometimes C), drug-induced liver injury (including anti-TB drugs and paracetamol overdose), ischaemic injury, autoimmune hepatitis.
• Very high (above 1,000 U/L): acute viral hepatitis, paracetamol or toxin injury, shock liver.

Cholestatic pattern (blocked or slowed bile flow)

ALP and GGT are raised out of proportion to ALT and AST, often with raised direct bilirubin.

• Gallstones in the bile duct
• Pancreatic or bile duct tumours
• Primary biliary cholangitis and primary sclerosing cholangitis
• Drug-induced cholestasis
• Liver infiltration (tuberculosis, cancers)

Mixed pattern

Both enzyme groups rise. Seen in many conditions, including drug injury and congestion from heart failure.

The R ratio (how doctors classify the pattern)

R = (ALT ÷ ALT upper limit) ÷ (ALP ÷ ALP upper limit)

• R above 5: hepatocellular
• R below 2: cholestatic
• R between 2 and 5: mixed

Example 1. ALT 280 U/L with an upper limit of 40, giving 7. ALP 120 U/L with an upper limit of 120, giving 1. R = 7 ÷ 1 = 7. This is a hepatocellular pattern.

Example 2. ALT 80 U/L (2 times the upper limit) and ALP 400 U/L with an upper limit of 120 (3.3 times). R = 2 ÷ 3.3 = 0.6. This is a cholestatic pattern.

The AST/ALT ratio

• AST/ALT ratio below 1 is typical of fatty liver and viral hepatitis.
• A ratio above 2 suggests alcohol-related liver disease, particularly with a high GGT.
• A ratio rising above 1 in a person with known fatty liver can hint at advancing fibrosis.

Common causes of abnormal LFTs in India

• Fatty liver (metabolic dysfunction-associated steatotic liver disease). Extremely common, related to belly fat, diabetes, high triglycerides and a sedentary life. Often the reason for mildly raised ALT.
• Alcohol-related liver disease.
• Viral hepatitis. Hepatitis A and E (contaminated food and water, with outbreaks in the monsoon), and hepatitis B and C (blood-borne).
• Medicines. Anti-tuberculosis drugs, paracetamol in excess, some antibiotics, anti-epileptics, statins (rarely), and herbal or "ayurvedic" preparations that may contain toxic substances.
• Dengue, typhoid, malaria and other infections, which can raise liver enzymes.
• Gallstones and bile duct problems.
• Autoimmune hepatitis and Wilson disease, more often in younger patients.
• Haemolysis, Gilbert's syndrome: raised indirect bilirubin with otherwise normal tests. Gilbert's syndrome is harmless and common.
• Heart failure congestion, thyroid disease, coeliac disease.
• Muscle injury and intense exercise, which can raise AST more than ALT.

Quick guide to bilirubin

| Pattern | Likely cause | |---|---| | High indirect (unconjugated) only | Haemolysis, Gilbert's syndrome, newborn jaundice | | High direct and total with high ALT/AST | Hepatitis, cirrhosis | | High direct with very high ALP/GGT | Bile duct obstruction | | Dark urine and pale stools | Obstructive jaundice |

Preparing for the test

• Fasting for 8 to 12 hours is usually requested if other tests are done together (such as lipid profile and glucose), but LFT itself does not strictly need it.
• Avoid alcohol for at least 24 to 72 hours.
• Avoid strenuous exercise the day before, because it can raise AST.
• Tell the lab and your doctor about all medicines, herbal products and supplements.
• Stay hydrated.

What to do about abnormal results

1. Don't ignore mild abnormalities, and don't panic. Repeat the test in a few weeks, since temporary rises happen.
2. See a doctor who will look at your history, examination, alcohol use, medicines and risk factors.
3. Further tests may include viral markers, ultrasound of the abdomen, a fibrosis assessment (FibroScan or FIB-4 score), iron studies, autoimmune markers, and in selected cases, CT, MRI or biopsy.
4. Stop alcohol if the liver is affected.
5. Review medicines. Don't stop prescribed medicines yourself; your doctor will decide. Avoid unregulated herbal remedies.
6. For fatty liver: lose 5 to 10 percent of body weight, walk daily, do strength training, cut sugary drinks and refined carbohydrates, improve blood sugar and cholesterol. This can reverse fatty liver and reduce enzyme levels.
7. Get vaccinated against hepatitis A and B if not immune.
8. Avoid over-the-counter painkillers in excess, especially paracetamol above the recommended daily maximum.

Warning signs

Go to a hospital promptly for:

• Jaundice with fever or abdominal pain
• Vomiting blood or black stools
• Abdominal swelling or leg swelling
• Confusion, drowsiness or a change in sleep pattern
• Very dark urine and pale stools
• Severe, persistent vomiting
• Bleeding or easy bruising

Frequently asked questions

What is SGOT?

SGOT is an older name for AST (aspartate aminotransferase), an enzyme found in the liver and other tissues. It rises when liver or muscle cells are damaged.

What is a normal SGPT level?

About 7 to 40 U/L, depending on the lab. SGPT is also called ALT.

What is the normal direct bilirubin?

Up to about 0.3 mg/dL.

Is a slightly raised SGPT serious?

A mild rise, often due to fatty liver, is common and usually not urgent, but should be evaluated and repeated.

Why is my SGOT higher than SGPT?

It can be due to alcohol use, advanced liver disease or muscle injury. A doctor will interpret it with the rest of the report.

Can LFT be done without fasting?

Yes, but follow your lab's instructions if other fasting tests are done together.

Can raised liver enzymes return to normal?

Often yes, once the cause (fatty liver, alcohol, a medicine, an infection) is treated.

When to see a doctor

See a doctor if any liver value is above range on repeat testing, if you have jaundice, dark urine, persistent fatigue, itching, abdominal pain or swelling, or if you take medicines that can affect the liver.

Care at Prakash Hospital Noida

Whether you live in Sector 18, Sector 62, Greater Noida West, or anywhere nearby, Prakash Hospital Noida is a trusted name for gastroenterology and liver care in Noida. Our specialists find the cause of abnormal liver tests and guide treatment and lifestyle change.

To book a consultation, call the number.

Sources: American College of Gastroenterology clinical guideline on evaluation of abnormal liver chemistries; standard clinical laboratory reference ranges. Ranges vary by laboratory.

Tags: #LiverFunctionTest #SGOTSGPT #PrakashHospitalNoida