Liver Function Tests Explained: What Do Your Numbers Mean?

When your doctor orders liver function tests, it’s natural to wonder what those results actually mean. Your liver is a vital organ that performs over 500 essential functions, including detoxifying your blood, producing proteins, and helping digest fat. But how do you interpret the numbers on your report? And what steps do you take if something seems off?

This blog is your guide to decoding liver function tests (LFTs). We’ll cover the most common markers, what they indicate, and how slight variations in your results might impact your health.

What Are Liver Function Tests?

Liver function tests are a group of blood tests that assess how well your liver is working. They measure levels of liver enzymes, proteins, and substances in the blood. Any irregularities can signal liver damage, inflammation, or other conditions affecting this organ. These tests are commonly ordered as part of routine check-ups or in response to symptoms like jaundice, abdominal pain, or persistent fatigue.

Why Are They Important?

Your liver is a powerhouse, constantly working to filter toxins, regulate nutrients, and produce essential compounds like bile. When your liver isn’t functioning properly, it can affect every system in your body. Catching irregularities early through LFTs allows doctors to address potential problems before they escalate.

Key Components of a Liver Function Test
Your LFT includes several key markers. Understanding these numbers is crucial to interpreting your results effectively.

1. Alanine Aminotransferase (ALT)

What it measures: ALT is an enzyme found primarily in the liver. High levels often indicate liver inflammation or damage, as ALT is released into the blood when liver cells are injured.
Common causes of elevated ALT: Conditions like hepatitis, excessive alcohol consumption, fatty liver disease, or even certain medications can cause ALT levels to spike.

2. Aspartate Aminotransferase (AST)

What it measures: Like ALT, AST is an enzyme located in your liver. However, it’s also found in other organs like the heart and muscles. Elevated AST levels might not always be liver-specific but could indicate liver damage when paired with high ALT.
AST-to-ALT ratio: This ratio can offer additional insight. For example, a high AST-to-ALT ratio could point to alcohol-related liver damage.

3. Alkaline Phosphatase (ALP)

What it measures: ALP is an enzyme found in the liver, bones, and bile ducts. High levels might suggest bile flow issues, such as blockages or gallstones, or liver disease.
When to investigate further: If ALP levels are elevated alongside other markers, your doctor may investigate bile duct conditions or bone disorders.

4. Bilirubin

What it measures: Bilirubin is a yellowish substance formed during the normal breakdown of red blood cells. Your liver processes bilirubin for elimination. Elevated levels indicate your liver isn’t functioning correctly or there’s an obstruction in bile flow, often resulting in jaundice.
Types of bilirubin: Direct (conjugated) bilirubin points to liver-related issues, while indirect (unconjugated) bilirubin is often related to excessive breakdown of red blood cells.

5. Albumin and Total Protein

What they measure: These tests assess the liver’s ability to produce essential proteins like albumin. Low levels may indicate chronic liver disease or other health concerns like malnutrition or kidney issues.
Why it matters: Albumin is crucial for maintaining fluid balance in your body, while other proteins play roles in fighting infections and blood clotting.

6. Gamma-glutamyl Transferase (GGT)

What it measures: GGT is an enzyme involved in bile production. Elevated levels might suggest bile duct issues or excessive alcohol consumption.
Interaction with lifestyle choices: Smoking and certain medications can also elevate GGT levels, so consider external factors when interpreting results.

7. Prothrombin Time (PT)

What it measures: PT assesses how quickly your blood clots. The liver produces clotting factors, so prolonged PT could indicate liver dysfunction.
Why it’s important: Elevated PT levels might require further evaluation, especially before surgical procedures.

What Do Abnormal Results Mean?

Abnormal LFT results don’t always spell trouble. Various factors, including temporary infections, alcohol intake, and recent illnesses, might influence your numbers. However, significant deviations could signal broader health concerns.

Potential Conditions Detected by Liver Function Tests

Hepatitis (A, B, C): Viral infections causing liver inflammation are often diagnosed through elevated ALT and AST levels.
Fatty Liver Disease: High ALT and triglyceride levels could indicate non-alcoholic fatty liver disease (NAFLD).
Cirrhosis: Chronic scarring of liver tissue results in elevated bilirubin and prolonged PT.
Alcoholic Liver Disease: A high AST-to-ALT ratio usually points to alcohol-related damage.
Bile Duct Issues: High ALP and bilirubin levels might indicate blockages or gallstones.

When Should You See a Doctor?

It’s essential to interpret LFT results in context. If your report shows consistently high levels across multiple markers or if you’re experiencing symptoms like jaundice, fatigue, or unexplained weight loss, consult your doctor immediately. They may recommend imaging studies (e.g., ultrasound or MRI) or a liver biopsy for further investigation.

Supporting Liver Health

Your liver is remarkably resilient and can regenerate when given the right care. Incorporating healthy habits into your lifestyle can support this vital organ:

1.   Limit Alcohol Intake: Excessive alcohol consumption is one of the leading causes of liver damage.

2.   Maintain a Balanced Diet: Foods rich in antioxidants, like leafy greens and berries, can help protect your liver from oxidative stress.

3.   Exercise Regularly: Physical activity lowers your risk of fatty liver disease.

4.   Stay Hydrated: Drinking plenty of water aids in the liver's detoxification process.

5.   Avoid Toxins: Limit exposure to harmful chemicals, including some cleaning agents and pesticides.

6.   Get Vaccinated: Vaccinations available for hepatitis A and B help prevent serious liver infections.

Empowering Yourself with Knowledge

Understanding your liver function test results empowers you to take charge of your health. These numbers paint a picture of what’s happening beneath the surface, helping you and your doctor make informed decisions.