Liver Function Tests (LFTs): What You Should Know

What Are Liver Function Tests?

Liver Function Tests (LFTs) are a collection of blood tests used to assess how well your liver is performing. They measure enzymes, proteins, and substances that either:

  • Reflect the liver’s normal activity, or

  • Leak into the blood when the liver is damaged.

When reviewed together with your medical history and symptoms, these results provide an overall picture of liver health. Both higher and lower values than expected may indicate a potential issue.


Why the Liver Matters

Your liver is one of the body’s most vital organs. It:

  • Processes nutrients from food.

  • Breaks down toxins and removes harmful by-products.

  • Produces bile, which helps digest fats.

  • Regulates blood clotting and stores essential vitamins and glycogen.

  • Plays a role in immunity by filtering bacteria and viruses from the bloodstream.

Because it performs so many crucial functions, damage to the liver can have widespread effects.

Why Doctors Recommend LFTs

Doctors may order LFTs if you:

  • Show symptoms of liver problems (e.g., jaundice, fatigue, abdominal pain).

  • Already have a diagnosed liver condition.

  • Need routine health screening.

  • Are taking medications that may affect liver function.

Often, LFTs are paired with other tests such as kidney function checks, a complete blood count, imaging (ultrasound, CT, MRI), or even a liver biopsy.

Common Causes of Liver Damage

Conditions that can harm the liver include:

Early liver damage may not show clear symptoms, which is why routine testing is valuable.


What Do LFTs Measure?

Test What It Shows
ALT (Alanine aminotransferase) Enzyme released when liver cells are damaged. Often rises early in liver disease.
AST (Aspartate aminotransferase) Another enzyme; high in liver damage but also affected by heart or muscle injury.
ALP (Alkaline phosphatase) Found in liver and bone; raised levels suggest liver or bile duct problems.
GGT (Gamma-glutamyl transferase) Helps confirm if high ALP is from liver disease rather than bone conditions.
Bilirubin A waste product from old red blood cells; high levels cause jaundice.
Albumin Main blood protein; low levels suggest long-term liver damage or kidney issues.

Other related tests may include total protein and prothrombin time (PT) to assess clotting.

Acute vs. Chronic Hepatitis

  • Acute Hepatitis: Appears suddenly, often with jaundice, dark urine, and severe illness. Commonly linked to hepatitis A, alcohol, drugs, or pregnancy-related liver issues.

  • Chronic Hepatitis: Lasts longer than six months, often with few symptoms except fatigue. Over time, it can progress to cirrhosis or liver failure.

How Is the Test Done?

  • Sample needed: A small blood draw.

  • Preparation: Usually none, though your doctor may advise fasting or pausing certain medications.

  • Results: Shown as numbers compared to “reference ranges.” Abnormal readings don’t always mean disease but should be interpreted in context with your history.

    Normal Ranges for Liver Function Tests (LFTs)

    🔹 ALT (Alanine Aminotransferase)

    • Women: 5 – 34 U/L

    • Men: 5 – 45 U/L

    🔹 ALP (Alkaline Phosphatase)

    • Women: 42 – 98 U/L

    • Men: 53 – 128 U/L
      (Children usually have higher levels)

    🔹 GGT (Gamma-Glutamyl Transferase)

    • Women: 5 – 50 U/L

    • Men: 5 – 35 U/L

    🔹 AST (Aspartate Aminotransferase)

    • Women: 7 – 31 U/L

    • Men: 7 – 35 U/L

    🔹 Bilirubin: 0.2 – 2.0 µmol/L
    🔹 Albumin: 3.5 – 5.2 mg/dL
    🔹 Total Protein: 6.4 – 8.3 mg/dL

FAQs About Liver Function Tests

Q1: Why would my doctor order LFTs?
LFTs are used for routine checkups, diagnosing possible liver problems, or monitoring existing conditions.

Q2: Do I need to fast before the test?
Not always. Your doctor will tell you if fasting is required.

Q3: Can abnormal results mean something other than liver disease?
Yes. Temporary conditions like infections, dehydration, or certain medicines can also cause unusual results.

Q4: What happens if my results are abnormal?
Your doctor may order more tests—such as imaging scans or a liver biopsy—to confirm the cause.

Q5: Can liver damage be reversed?
In early stages, lifestyle changes, avoiding alcohol, and proper treatment can allow the liver to heal. Advanced scarring (cirrhosis) is usually permanent.

Q6: What lifestyle steps help protect the liver?
Maintain a healthy weight, limit alcohol, avoid unnecessary medications, get vaccinated for hepatitis, and eat a balanced diet.

Key Takeaway

Liver Function Tests are essential for detecting early problems before symptoms appear. They don’t diagnose one single condition but provide valuable clues to guide further care. By getting tested regularly and making lifestyle adjustments, you can protect one of your body’s hardest working organs.

Also Read
Significance of Liver Function Test


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