Liver Function Test (LFT)

What is the LFT test?

LFT parameters11 measured

1. Bilirubin — total

   0.2–1.2 mg/dL

   The yellow pigment left when old red cells are broken down, rising when the liver is inflamed, bile is blocked or red cells break down too fast

2. Bilirubin — direct

   up to 0.3 mg/dL

   The portion of bilirubin the liver has already processed, rising when bile cannot drain because of gallstones, blockage or liver damage

3. Bilirubin — indirect

   0.1–1 mg/dL

   The portion of bilirubin not yet processed by the liver, rising when red cells break down quickly or in the harmless Gilbert's syndrome

4. SGPT (ALT)

   10–49 U/L

   Alanine aminotransferase, an enzyme that leaks from injured liver cells, rising with fatty liver, viral hepatitis, alcohol or some medicines

5. SGOT (AST)

   15–40 U/L

   Aspartate aminotransferase, an enzyme from liver and muscle cells, rising with liver injury, alcohol, heavy exercise or heart muscle damage

6. Alkaline phosphatase

   30–120 U/L

   An enzyme from bile ducts and bone, rising when bile flow is blocked, in growing children, in pregnancy or with bone conditions

7. GGT

   up to 73 U/L

   Gamma-glutamyl transferase, a bile duct enzyme that rises early with alcohol excess, fatty liver or blocked bile, confirming a raised ALP comes from the liver

8. Total protein

   5.7–8.2 g/dL

   All the proteins in the blood together, falling with poor nutrition, liver or kidney disease and rising with dehydration or chronic inflammation

9. Albumin

   3.2–4.8 g/dL

   The main protein made by the liver that holds fluid in the blood vessels, falling with liver disease, kidney leakage or poor nutrition

10. Globulin

    2–3.5 g/dL

    The group of proteins that includes antibodies, rising with chronic infection, inflammation or immune disorders and falling when antibody production is weak

11. A/G ratio

    1–2.1 ratio

    Albumin to globulin ratio, comparing the liver's main protein against the immune proteins, falling with liver disease, kidney leakage or chronic inflammation

Reference ranges are the lab's defaults for adults and are printed on the report beside every value

How to prepare

• Fast for 10 hours before the sample. Water is fine.
• Avoid alcohol for 24 hours before the test, as it can push GGT and SGOT up.
• Take regular medicines as usual unless your doctor says otherwise, and tell the phlebotomist what you take.
• Skip heavy exercise the evening before; it can raise SGOT.

Who should take it

Anyone with yellow eyes or skin, dark urine, pale stools, or pain under the right ribs. People who drink alcohol regularly. Anyone starting or continuing statins, anti-tuberculosis treatment, methotrexate, antifungals or long courses of painkillers. People with type 2 diabetes, obesity or a family history of liver disease, once a year. Anyone with a positive hepatitis B or C result, for monitoring. It is also part of most pre-surgery and annual health checks.

Before the visit

Tell your doctor about alcohol intake, paracetamol use, ayurvedic or herbal preparations, bodybuilding supplements and any recent viral illness. All of these can move liver enzymes without permanent damage.

Why take the LFT test?

• Alcohol and the liver: Regular drinking raises GGT and SGOT long before any symptom appears.
• Medicines that strain the liver: Statins, anti-tuberculosis drugs, methotrexate and some painkillers need a baseline LFT and periodic checks.
• Fatty liver: A raised SGPT is often the first sign in people with diabetes, a large waist or high triglycerides.
• Jaundice or dark urine: The bilirubin split tells the doctor whether the problem is in the liver or in the bile ducts.
• Tiredness with no clear cause: Persistent fatigue, nausea or itching are worth a liver check.

Questions about the LFT test