Liver Function Test (LFT)

Your liver is one of the most vital organs in your body. It plays a key role in digestion, metabolism, detoxification, and nutrient storage. However, many liver diseases often go unnoticed until they reach advanced stages. That’s why Liver Function Tests (LFTs) are essential—they provide a quick and accurate way to check how well your liver is working.

In this blog, we’ll cover everything you need to know about the Liver Function Test: what it is, why it’s done, how to prepare, what the results mean, and frequently asked questions.

What is a Liver Function Test (LFT)?

A Liver Function Test (LFT) is a group of blood tests that measure different enzymes, proteins, and substances in the blood. These markers help doctors assess the liver’s overall health and detect liver damage, infection, or disease.

LFTs are not a single test but a panel of tests that together give a complete picture of liver function.

Why is the Liver Function Test Important?

The liver performs more than 500 functions in the body. A damaged liver can affect:

• Digestion and nutrient absorption

• Energy metabolism

• Detoxification of harmful substances

• Blood clotting

• Hormonal balance

An LFT helps in early detection of conditions like:

• Hepatitis (viral infections of the liver)

• Fatty liver disease (alcoholic and non-alcoholic)

• Cirrhosis

• Liver cancer

• Gallbladder disease

• Side effects of certain medications

Components of a Liver Function Test

An LFT panel usually includes the following parameters:

1. Alanine Aminotransferase (ALT)

• An enzyme found in the liver.

• Elevated ALT levels indicate liver injury or inflammation.

2. Aspartate Aminotransferase (AST)

• Found in the liver, heart, and muscles.

• High AST levels suggest liver or muscle damage.

3. Alkaline Phosphatase (ALP)

• An enzyme linked to bile ducts.

• Elevated ALP may indicate blocked bile ducts, liver disease, or bone disorders.

4. Gamma-Glutamyl Transferase (GGT)

• Helps detect bile duct issues and alcohol-related liver damage.

5. Bilirubin (Total and Direct)

• A yellow pigment formed from the breakdown of red blood cells.

• High bilirubin causes jaundice and indicates poor liver function.

6. Albumin and Total Protein

• Proteins made by the liver.

• Low levels indicate poor liver function, malnutrition, or kidney disease.

7. Prothrombin Time (PT/INR)

• Measures how quickly blood clots.

• A prolonged PT suggests impaired liver function.

Normal Ranges for LFT Parameters

(Note: Ranges may slightly vary depending on the lab.)

• ALT (SGPT): 7–56 units/L

• AST (SGOT): 10–40 units/L

• ALP: 44–147 IU/L

• GGT: 9–48 IU/L

• Total Bilirubin: 0.1–1.2 mg/dL

• Direct Bilirubin: 0–0.3 mg/dL

• Albumin: 3.5–5.0 g/dL

• Total Protein: 6.0–8.3 g/dL

• Prothrombin Time (PT): 11–13.5 seconds

When Should You Get a Liver Function Test?

Doctors may recommend an LFT if you have:

• Symptoms of liver disease:

  • Yellowing of skin/eyes (jaundice)

  • Dark urine

  • Fatigue and weakness

  • Abdominal swelling or pain

  • Unexplained nausea or vomiting

• Risk factors for liver damage:

  • Alcohol consumption

  • Hepatitis infections (B, C)

  • Family history of liver disease

  • Obesity and diabetes

  • Long-term medication use

• As part of routine health check-ups

How is a Liver Function Test Done?

The LFT is a simple blood test:

1. A phlebotomist draws a small blood sample from your vein (usually in the arm).

2. The sample is analysed.

3. Results are available within 24 hours.

How to Prepare for an LFT

• Fasting: Some labs may require 8–12 hours of fasting, especially if additional tests like lipid profile are ordered.

• Medication: Inform your doctor about any medications, supplements, or herbal products you’re taking, as some can affect results.

• Alcohol: Avoid alcohol for at least 24–48 hours before the test.

Interpreting LFT Results

• High ALT & AST: May indicate hepatitis, fatty liver, or cirrhosis.

• High ALP & GGT: Suggests bile duct obstruction or alcohol-related damage.

• High Bilirubin: Indicates jaundice, gallstones, or hemolysis.

• Low Albumin/Protein: Suggests chronic liver disease or malnutrition.

• Prolonged PT: Suggests impaired liver function affecting clotting.

Important: Abnormal results do not always mean severe disease. Further diagnostic tests (like ultrasound, CT scan, MRI, or liver biopsy) may be required.

Risks of the Test

LFT is safe and simple, with minimal risks such as:

• Slight pain or bruising at the needle site

• Rarely, dizziness or fainting

How Often Should You Get an LFT?

• Routine health check-up: Once a year if you are at risk

• Monitoring chronic conditions: More frequent if you have hepatitis, fatty liver, or are on long-term medication

• Alcohol users: At least twice a year

Lifestyle Tips to Maintain Healthy Liver Function

• Limit alcohol consumption

• Maintain a healthy weight

• Eat a balanced diet (fruits, vegetables, lean proteins, whole grains)

• Avoid excessive fatty and fried foods

• Get vaccinated against hepatitis A & B

• Exercise regularly

• Avoid self-medication and unnecessary supplements

• Stay hydrated

A Liver Function Test (LFT) is a vital diagnostic tool to evaluate liver health. It helps in early detection of liver disease, guides treatment decisions, and monitors ongoing liver conditions. Regular check-ups, combined with a healthy lifestyle, can keep your liver functioning optimally.

If you experience symptoms of liver disease or are at risk, consult your doctor and get your LFT done without delay.

FAQ Section

1. What is the most common reason for an abnormal LFT?

The most common causes include fatty liver disease, alcohol consumption, hepatitis, and medication side effects.

2. Can LFT detect liver cancer?

LFTs can indicate liver damage but cannot directly diagnose cancer. Further imaging and biopsy are needed.

3. Do I need to fast before an LFT?

Fasting is not always required, but some labs recommend it if additional tests are included.

4. How long does it take to get LFT results?

Usually within 24 hours.

5. Can I drink alcohol before the test?

No. Alcohol can temporarily elevate liver enzymes and distort results. Avoid it at least 24–48 hours before testing.

6. How often should I check my liver function?

At least once a year if you are at risk, and more frequently if you have a chronic liver condition.

7. What happens if my LFT is abnormal?

Your doctor may order further tests (ultrasound, CT scan, MRI, or biopsy) to confirm the cause and guide treatment.

8. Is LFT painful?

No. It is just a simple blood test with minimal discomfort.

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