Medically reviewed by Dr. Hafiz Muhammad Haseeb, M.B.B.S., F.C.P.S. (Haematology), Consultant Haematologist, Al-Nasar Lab & Diagnostic Centre. Updated August 2026.
Quick answer: A Liver Function Test is a blood test measuring enzymes and proteins that show how well your liver is working. The key values are ALT and AST, which rise when liver cells are damaged, ALP and GGT, which rise when bile flow is blocked, and bilirubin, which causes jaundice when it builds up.
Book an LFT: call 0300 0341944, or arrange home sample collection across Lahore on 0309 1166944.
What does a liver function test check?
Despite the name, an LFT does not measure a single function. It is a panel of separate markers, and the pattern between them is what tells the story. Two people can both have an abnormal LFT for completely different reasons, and it is the shape of the abnormality that points a doctor in the right direction.
| Marker | What it indicates | Typical adult range |
|---|---|---|
| ALT (SGPT) | Damage to liver cells. The most liver specific marker on the panel | roughly 7 to 55 U/L |
| AST (SGOT) | Damage to liver cells, but also found in muscle and heart | roughly 8 to 48 U/L |
| ALP | Bile duct blockage. Also comes from bone | roughly 40 to 130 U/L |
| GGT | Bile duct problems, and sensitive to alcohol and certain medicines | roughly 8 to 61 U/L |
| Total bilirubin | The pigment that causes jaundice when it accumulates | roughly 0.1 to 1.2 mg/dL |
| Albumin | A protein the liver makes. Low values suggest long standing disease | roughly 3.5 to 5.5 g/dL |
Ranges vary between laboratories and analysers, so always read the reference range printed on your own report rather than comparing against a general figure.
What does a raised ALT or AST mean?
Raised ALT and AST indicate that liver cells are being injured and are leaking their contents into the blood. The most common reasons in Pakistan are fatty liver disease, which is increasingly common alongside diabetes and excess weight, viral hepatitis, particularly hepatitis B and C, and medication effects, including some painkillers, herbal remedies and tuberculosis treatment.
The size of the rise matters. A mild elevation is often related to fatty liver and responds to weight and lifestyle changes. A very high reading suggests active inflammation and needs prompt investigation.
What does a raised ALP or bilirubin mean?
When ALP and GGT rise together, the pattern points toward the bile ducts rather than the liver cells themselves. This can be caused by gallstones blocking a duct, inflammation, or a narrowing. When bilirubin rises alongside them, the skin and the whites of the eyes may turn yellow, which is jaundice.
If your doctor suspects a blockage, imaging usually follows. An ultrasound is often first, and an MRCP scan gives a detailed view of the bile ducts without any invasive procedure.
Do you need to fast for an LFT?
Many laboratories advise fasting for eight to twelve hours, mainly because a recent fatty meal can alter some values and because LFTs are often ordered together with a lipid profile or blood sugar, which do require fasting. Water is allowed and encouraged.
Also tell the laboratory about any medicines, supplements or herbal preparations you take, since several can affect liver enzymes and knowing about them changes how the result is interpreted.
Who should have a liver function test?
- Persistent tiredness, nausea, or pain in the upper right abdomen
- Yellowing of the skin or eyes, dark urine, or pale stools
- Known or suspected hepatitis B or C
- Diabetes, obesity or high cholesterol, all of which raise the risk of fatty liver
- Regular use of medicines known to affect the liver, including long term painkillers and tuberculosis treatment
- Before starting certain medications, and periodically while taking them
- As part of a general health check
What happens if your LFT is abnormal?
An abnormal result is a starting point, not a diagnosis. Mild changes are common and often resolve. Your doctor will look at the pattern across all the markers, consider your symptoms and medicines, and may repeat the test after a few weeks. Further steps can include hepatitis screening, an ultrasound of the abdomen, or a complete blood count to give a fuller picture.
Liver function testing at Al-Nasar Lab
Al-Nasar Lab & Diagnostic Centre has run laboratory testing in Lahore since 1996 and holds ISO 15189:2022 accreditation from the Pakistan National Accreditation Council. Liver function testing is available at our main Johar Town campus and at every collection centre, with home sample collection and same day digital reports. Our main campus also provides ultrasound and MRCP, so if imaging is needed it can usually be arranged in the same place.
Find your nearest collection centre, see our full test list, or contact us to book.
Frequently Asked Questions
What is a normal ALT level?
Roughly 7 to 55 U/L for adults, though ranges differ between laboratories. Read the range printed on your own report.
Can a liver function test detect fatty liver?
It can suggest it. Mildly raised ALT and AST are a common sign of fatty liver, but an ultrasound is usually needed to confirm it, since the blood test alone cannot see the liver.
Do I need to fast for an LFT?
Fasting for eight to twelve hours is commonly advised, particularly when the LFT is combined with a lipid profile or blood sugar test. Water is allowed.
Can a normal LFT rule out liver disease?
Not entirely. Some people with established liver disease have normal enzymes, especially in the early stages or in long standing scarring. That is why doctors combine the blood test with imaging and your history.
How long does an LFT report take?
Liver function results are generally available the same day at Al-Nasar Lab, delivered as a digital report.
This article is for general information and is not a substitute for medical advice. Please discuss your results with a qualified doctor.
