Liver Function Tests Explained: A Complete Guide

Liver Function Tests (LFTs), also known as a liver panel, are a group of blood tests used to assess liver health and identify signs of liver injury or disease. The liver performs several essential functions, including helping with digestion, processing nutrients, storing energy, removing waste products, and producing important proteins.

An LFT can provide valuable information about how the liver and related systems are functioning. Doctors may recommend these tests as part of routine health monitoring or when symptoms suggest a possible liver problem.

What Does a Liver Function Test Measure?

A liver panel may include several different tests. The exact combination can vary depending on the laboratory and the reason for testing.

Albumin and Total Protein

Albumin is a protein produced by the liver that helps maintain fluid balance in the bloodstream and transports various substances throughout the body. Total protein measures the overall amount of protein in the blood.

Abnormal levels can occur for several reasons, including liver disease, nutritional problems, kidney conditions, and other health issues. They should therefore be interpreted along with other test results.

Bilirubin

Bilirubin is produced when red blood cells are broken down. The liver processes bilirubin and helps remove it from the body.

When bilirubin levels become elevated, a person may develop jaundice, which can cause yellowing of the skin and whites of the eyes. High bilirubin levels can have several causes, so further evaluation may be required.

ALT and AST

ALT (Alanine Aminotransferase) and AST (Aspartate Aminotransferase) are enzymes that can enter the bloodstream when cells are damaged.

Elevated ALT and AST levels may be associated with liver inflammation or injury. However, these enzymes can also be affected by conditions outside the liver, so abnormal results do not necessarily indicate a specific liver disease.

ALP and GGT

ALP (Alkaline Phosphatase) and GGT (Gamma-Glutamyl Transferase) can provide information about the liver and biliary system.

Elevated ALP may be associated with problems involving the bile ducts, although it can also increase because of certain bone conditions. GGT may also rise in several liver and bile duct disorders. Doctors generally interpret these values together with other LFT results and the patient's symptoms.

Prothrombin Time (PT)

Prothrombin Time (PT) measures how long it takes blood to clot. Because the liver produces several proteins involved in blood clotting, severe liver dysfunction can affect PT.

PT may also be influenced by other factors, including certain medications and vitamin K levels.

Why Are Liver Function Tests Done?

Doctors may recommend LFTs for several reasons, including:

• Checking for possible liver disease or liver injury

• Investigating symptoms that may be related to the liver

• Assessing the severity of an existing liver condition

• Monitoring liver health over time

• Checking whether treatment is working

• Monitoring for possible liver-related effects of certain medicines

LFTs may also be requested as part of an evaluation when a person has risk factors for liver disease.

SERUM ALB/GLOBULIN RATIO

ALKALINE PHOSPHATASE

1 param →

BILIRUBIN -DIRECT

1 param →

BILIRUBIN (INDIRECT)

BILIRUBIN - TOTAL

1 param →

GAMMA GLUTAMYL TRANSFERASE (GGT)

1 param →

SGOT / SGPT RATIO

PROTEIN - TOTAL

1 param →

ALBUMIN - SERUM

1 param →

SERUM GLOBULIN

1 param →

ASPARTATE AMINOTRANSFERASE (SGOT )

1 param →

ALANINE TRANSAMINASE (SGPT)

Symptoms That May Require Liver Testing

A healthcare professional may consider liver testing when someone experiences symptoms such as:

• Loss of appetite

• Nausea or vomiting

• Persistent fatigue or weakness

• Swelling in the legs or ankles

• Abdominal pain or swelling

• Yellowing of the skin or eyes

• Persistent itching

• Dark-colored urine

• Pale or clay-colored stools

These symptoms can have many different causes, so an LFT alone cannot determine the underlying condition.

How Is a Liver Function Test Performed?

An LFT is usually performed using a blood sample collected from a vein, typically in the arm. The sample is then sent to a diagnostic laboratory for analysis.

Whether fasting is required depends on the specific tests included in the panel and the laboratory's instructions. It is important to inform your healthcare provider about any medicines, vitamins, or supplements you take, as some substances can influence laboratory results.

Understanding Your LFT Results

LFT results are generally reported with reference ranges provided by the laboratory. A result outside the reference range does not automatically mean that a person has liver disease.

Doctors consider the individual values together with symptoms, medical history, medications, physical examination, and sometimes additional investigations such as imaging or other blood tests.

Conclusion

Liver Function Tests are an important tool for evaluating liver health and investigating possible liver or bile duct problems. Because an LFT includes several different markers, looking at the overall pattern of results is often more useful than focusing on a single number.

If you have symptoms that may be associated with liver problems or have been advised to monitor your liver health, consult a qualified healthcare professional about the appropriate tests and how to interpret the results.