Understanding Your Liver Function Test (LFT)
Your liver is one of the hardest-working organs in your body. It helps filter toxins, process nutrients, produce proteins, and support digestion. Because many liver conditions develop silently without obvious symptoms, a Liver Function Test (LFT) is an important tool for assessing liver health.
In my practice, I often recommend an LFT as part of a routine health screening or when patients have symptoms or medical conditions that may affect the liver.
What Is a Liver Function Test?
A Liver Function Test is a group of blood tests that evaluates how well your liver is functioning. It typically measures:
- Alanine aminotransferase (ALT)
- Aspartate aminotransferase (AST)
- Alkaline phosphatase (ALP)
- Gamma-glutamyl transferase (GGT)
- Bilirubin
- Albumin
- Total protein
Together, these markers provide valuable information about liver cell health, bile flow and the liver’s ability to perform its essential functions.
Why Is the Liver So Important?
Your liver plays a vital role in:
- Filtering toxins from the bloodstream
- Processing medications
- Producing proteins and clotting factors
- Storing vitamins and minerals
- Regulating metabolism
- Producing bile to aid digestion
When liver function is affected, many of these processes can become impaired.
Why Might Your Doctor Recommend an LFT?
An LFT may be recommended if you:
- Experience persistent fatigue
- Develop yellowing of the skin or eyes (jaundice)
- Have abdominal discomfort
- Have diabetes or obesity
- Consume alcohol regularly
- Take medications that may affect the liver
- Have a history of viral hepatitis
- Are undergoing routine health screening
Understanding Your Results
ALT and AST
These enzymes are found inside liver cells. Elevated levels may suggest liver cell inflammation or injury, although they do not identify the exact cause.
ALP and GGT
These markers help assess the bile ducts and may become elevated in certain liver or gallbladder conditions.
Bilirubin
Bilirubin is a waste product processed by the liver. High levels may lead to jaundice and can indicate liver or bile duct problems.
Albumin and Total Protein
These tests assess the liver’s ability to produce important proteins. Low levels may occur in chronic liver disease and other medical conditions.
Do You Need to Fast?
Most Liver Function Tests do not require fasting. However, if your doctor has ordered additional blood tests, such as cholesterol or glucose, fasting instructions may be provided.
Can an LFT Diagnose Liver Disease?
A Liver Function Test is an excellent screening tool, but it cannot diagnose every liver condition on its own. Abnormal results may require further assessment, including additional blood tests, ultrasound imaging or referral to a specialist.
When Should You See a Doctor?
Seek medical evaluation if you experience:
- Persistent fatigue
- Yellowing of the skin or eyes
- Dark urine
- Pale stools
- Abdominal swelling
- Ongoing nausea
- Unexplained weight loss
Early assessment can help identify liver problems before they become more serious.
Doctor's Insight
In my practice, I remind patients that liver disease often develops quietly, especially in its early stages. A Liver Function Test provides valuable information about liver health and can help detect abnormalities before symptoms appear. Combined with a healthy lifestyle and regular health screening, it is an important step in protecting your long-term wellbeing.
– Dr. Teh Boon Teong
Consultant in Internal Medicine
Evercare Medical Care Centre, Penang, Malaysia.
Frequently Asked Questions
It is a blood test that measures enzymes and proteins to assess how well your liver is functioning.
Usually not, unless other fasting blood tests are being performed at the same time.
They are liver enzymes that may become elevated when liver cells are inflamed or injured.
No. It provides important information about liver health but may need to be combined with other tests for a diagnosis.
Individuals with diabetes, obesity, regular alcohol intake, certain medication use, a history of liver disease or those undergoing routine health screening.