Liver Function Tests: Types, Purpose & Results Interpretation

With the rise in liver-related ailments in India, understanding liver function tests (LFTs) has never been more important. The liver performs over 500 essential functions, including detoxifying blood, producing proteins, and regulating cholesterol levels. A disruption in these functions can manifest as critical health issues.

What Are Liver Function Tests?

Liver function tests are blood tests that measure various enzymes, proteins, and substances produced or processed by the liver. These tests help gauge liver health, diagnose potential issues, or monitor chronic conditions like cirrhosis or hepatitis.

Why Liver Function Tests Are Vital

Liver diseases are on the rise in India due to factors such as excessive alcohol consumption, viral infections (hepatitis B and C), fatty liver disease, and the growing prevalence of obesity and diabetes. Early detection through liver function tests can help in timely intervention and better outcomes.

Key purposes for LFTs include:

Early Detection of liver diseases like hepatitis or liver cancer.
Monitoring Ongoing Conditions such as fatty liver disease or cirrhosis.
Evaluating Treatments for known liver conditions or the side effects of certain medications.
General Health Assessments as part of routine health check-ups.

Common Symptoms That May Warrant Liver Function Tests

Your doctor may recommend liver function tests if you’re experiencing symptoms such as:

Fatigue without a clear cause
Jaundice (yellowing of the skin and eyes)
Chronic nausea or vomiting
Persistent abdominal pain or swelling
Unexplained weight loss
Dark-colored urine or pale stools

Types of Liver Function Tests

Liver function tests assess multiple aspects of liver health. Here’s an overview of the most common LFTs:

1. Alanine Transaminase (ALT)

ALT is an enzyme that helps break down proteins in the liver. Elevated levels indicate liver damage or inflammation.
Normal range: 7–55 U/L

2. Aspartate Transaminase (AST)

AST is found in the liver, heart, and other muscles. While its elevation isn’t specific to liver issues, it’s frequently evaluated alongside ALT for a more comprehensive analysis.
Normal range: 8–48 U/L

3. Alkaline Phosphatase (ALP)

ALP is an enzyme found in the liver and bile ducts. Increased ALP levels may point to blocked bile ducts or diseases affecting the bile flow.
Normal range: 45–115 U/L

4. Bilirubin

Bilirubin is a yellow pigment formed during the breakdown of red blood cells. The liver processes bilirubin, and high levels may indicate jaundice or liver malfunction.

Total bilirubin Normal range: 0.1–1.2 mg/dL
Direct bilirubin (conjugated) and indirect bilirubin (unconjugated) are also measured for detailed analysis.

5. Albumin and Total Protein

The liver produces albumin, a vital protein that maintains fluid balance in the body. Low albumin levels suggest chronic liver or kidney dysfunction.
Normal albumin range: 3.5–5.0 g/dL

6. Gamma-Glutamyl Transferase (GGT)

GGT helps determine if bile ducts are functioning correctly. Elevated levels may indicate bile duct or liver damage, often linked with alcohol use.
Normal range: 9–48 U/L

7. Prothrombin Time (PT)

The liver produces clotting factors; PT assesses how long it takes for blood to clot. A prolonged clotting time might indicate a reduced ability of the liver to produce these factors.
Normal range: 11–13.5 seconds

8. Lactate Dehydrogenase (LDH)

An enzyme involved in energy production, an increase in LDH levels can signal liver damage.
Normal range: 140–280 U/L

9. Total Globulin Levels

This test measures all the proteins apart from albumin. It helps diagnose whether the liver or immune system is compromised.
Normal range depends on the type of globulin, commonly around 2.6–4.6 g/dL.

Interpreting Liver Function Test Results

Understanding LFT results requires professional expertise to evaluate each parameter, its range, and how they correlate with potential liver conditions. Here are some general guidelines:

Mildly Elevated Levels may indicate temporary inflammation or minor issues such as a recent viral infection.
Moderate Elevations often warrant additional diagnostic tests to pinpoint the cause.
Severely Abnormal Levels indicate serious liver damage or advanced disease requiring immediate treatment.

Here are some key interpretations:

Elevated ALT/AST levels may point to hepatitis or fatty liver disease.
Elevated ALP levels can be a marker for bile duct obstruction or bone disease.
High bilirubin levels suggest jaundice or liver’s inability to process red blood cells properly.
Low albumin levels could indicate chronic liver disease or malnutrition.

Steps to Prepare for a Liver Function Test

To ensure accurate results:

Fast if Necessary: Some LFTs may require fasting for 8–12 hours.
Avoid Alcohol a day or two before the test.
Inform Your Doctor about medications, as certain drugs can alter liver enzyme levels.

Managing and Preventing Liver Diseases in India

Liver diseases contribute significantly to the healthcare burden in India, making awareness and prevention paramount. Here are practical steps to keep your liver healthy:

Limit Alcohol consumption, as excessive intake leads to liver damage.
Maintain a Healthy Weight through diet and exercise to prevent non-alcoholic fatty liver disease (NAFLD).
Get Vaccinated against hepatitis A and B.
Avoid Medications and Toxins that strain the liver without medical advice.
Regular Check-ups to monitor liver health proactively.

Conclusion

Liver function tests are invaluable in detecting irregularities early and ensuring timely medical intervention. With enhanced understanding of what these tests entail, you’re now better equipped to maintain your health and well-being.

For those who suspect potential liver issues or simply want to stay proactive, consult a healthcare provider and schedule your liver function test today. Prioritize your liver's health now to ensure a healthier future.