The liver is your body's largest internal organ and its ultimate multitasker — detoxifying the blood, producing proteins, storing energy, and aiding digestion. A Liver Function Test (LFT) measures whether your liver is working as it should.
What Does an LFT Measure?
SGPT (ALT — Alanine Aminotransferase)
The most liver-specific enzyme. When liver cells are damaged, SGPT leaks into the bloodstream.
- Normal range: 7–56 U/L
- Elevated in: viral hepatitis, fatty liver disease, medication toxicity, alcohol use
SGOT (AST — Aspartate Aminotransferase)
Present in the liver, heart, and muscles. Elevated in liver disease, but also in heart attacks and muscle injury.
- Normal range: 10–40 U/L
ALP (Alkaline Phosphatase)
Elevated in liver, bone, and bile duct conditions.
- Normal range: 44–147 U/L (adults)
Serum Bilirubin (Total, Direct, Indirect)
Bilirubin is a yellow pigment produced when red blood cells break down. Elevated bilirubin causes jaundice (yellowing of skin and eyes).
- Total bilirubin normal: 0.1–1.2 mg/dL
- Elevated in: hepatitis, cirrhosis, gallstones, hemolytic anemia
Serum Albumin
Protein made by the liver. Low albumin indicates chronic liver disease or malnutrition.
- Normal range: 3.5–5.0 g/dL
PT/INR (Prothrombin Time)
Measures clotting ability. Since the liver produces many clotting factors, a prolonged PT indicates serious liver dysfunction.
Who Should Get an LFT?
- People who drink alcohol regularly
- Those on long-term medications (statins, antibiotics, painkillers)
- People with diabetes or obesity
- Anyone with symptoms of jaundice, abdominal pain, or unexplained fatigue
- As part of an annual health checkup after age 30
Protecting Your Liver
- Limit alcohol consumption
- Maintain a healthy weight
- Get vaccinated for Hepatitis A and B
- Avoid unnecessary medications and supplements
- Exercise regularly and eat a plant-rich diet