Liver Function Test – LFT


Last Updated December 20th, 2021

What is the Liver Function Test?

A Liver Function Test or LFT refers to a group of blood tests that provide a complete insight into how well a person’s liver is functioning. It is often referred to as a hepatic panel and consists of testing important biomarkers such as ALT ( alanine transaminase) that are accurate indicators of hepatic health.

It is one of the most commonly prescribed blood tests both in primary and secondary healthcare. It is usually ordered for those patients who show symptoms of liver injury or liver disease such as hepatic jaundice.

How widespread are liver diseases in India?

As per WHO, liver diseases are the 10th most common cause of fatalities in India. More than 1 million new cases of liver cirrhosis are reported every year. The most common cause of chronic liver disease in India is Hepatitis B in the non-alcohol drinking population. Speaking in global terms, every year the world witnesses 2 million deaths owing to liver diseases.

What is the importance of a Liver Function Test?

LFT results provide critical information on the condition of the liver. If there is any damage or inflammation in the hepatic tissues, it can be detected early on by this test and further (and irreversible) damage to the liver can be deterred.

It is important to note that this is not a routine blood test and is prescribed only under those conditions where the patient shows symptoms of liver dysfunction. Mostly, LFT is done to screen liver diseases such as liver cirrhosis or obstructive jaundice. It is also done to monitor the side-effects of the medications that you are on, in case those drugs have mild to moderate hepatotoxic properties.

At times, LFT can also be used as a diagnostic tool to measure the efficacy of the current liver treatment a patient might be undergoing and monitor the improvements in liver health.

What are the main functions of the liver?

The liver is counted as a vital organ as it not only serves critical functions in the body but also because any damage or inflammation in this organ can have serious (and sometimes fatal) complications. Located in the upper right part of the abdomen, the liver is responsible for detoxification of metabolites such as glucose and the red blood cells. It is also required for glycogen storage and biosynthesis of digestive enzymes.

Additionally, the liver is also recognized as an accessory digestive organ because it produces the enzyme, bile, which is a fluid mixture of cholesterol and bile acids that helps in the breakdown of fats in the human body. The liver also controls and regulates a large number of high-volume biochemical reactions within the body (as high as 500) which are critical to almost every vital bodily process.

Thus, it can be easily concluded that any disease, infection, or trauma that impacts the liver can have drastic consequences. It is thus important to either rule out or correctly diagnose any type of liver damage or disease in the initial stage itself, with the help of LFT, to mitigate further damage to the body.

Why has my doctor prescribed me an LFT?

LFT is prescribed when an individual shows the following symptoms:

– Signs of a liver infection such as hepatitis A, B, or C – yellowish coloration of skin (jaundice), abdominal pain, digestive disorders, and high fever.

– Unexplained weight loss, nausea, and vomiting.

– The dark brown color of urine (often a sign of hepatitis B; an STD) and greyish/ tar colored stools.

– Itching of skin

Chronic fatigue and a general sense of malaise

– Swelling of limbs and ankles (edema)

– Easy bruising and bleeding

It might also be prescribed to check the progression of diseases such as alcoholic hepatitis and whether the treatment for the same is working or not.

What biomarkers/enzymes are tested via a Liver Function Test?

The levels of the following enzymes are observed by the help of an LFT:

– Alanine aminotransferase (ALT)
– Alkaline phosphatase (ALP)
– Aspartate aminotransferase (AST)
Gamma-glutamyl transferase (GGT)
– Albumin
– Total protein 
– Prothrombin time (PT)
– Lactate dehydrogenase (LDH)

How is the LFT procedure performed?

The LFT is a blood test where the blood sample is collected from the vein in the arm. A tight elastic band is tied around your upper arm to locate the vein correctly. Once the vein has been located, a syringe is inserted in the vein and blood is drawn and collected in a vial. The entire procedure doesn’t take more than a few minutes. It is a relatively painless procedure and you might feel a slight sting when the needle is inserted. You can go home as soon as the blood sample collection is done.

What do the levels of these liver enzymes indicate?

Liver Enzyme Abnormal Value indicates
ALTHigh value indicates liver damage. Low value is considered normal.
ASTA high value indicates hepatitis, cirrhosis, or tumor. A low value is treated as normal reading.
ALPA low level can be either caused by zinc deficiency or bypass surgery. High level is indicative of liver disease, bone diseases, or even ulcerative colitis.
AlbuminLow value could mean acute liver disease, kidney disease, malnutrition and malabsorption, cancer, or diabetes. High-level could be caused by dehydration.
Total ProteinA low level indicates either kidney or liver dysfunction while a higher value is either a sign of infection or bone marrow disorders.
BilirubinA low level of bilirubin is considered normal. A high level is associated with anemia, cirrhosis, a side-effect of drugs, or even cancer.
GGTLow GGT level means healthy liver functioning. High GGT indicates damage to the liver ducts.
LDHHigh LDH level is indicative of a number of serious diseases and disorders such as sepsis, testicular cancer, anemia, pancreatitis, in addition to liver inflammation. A low level is normal reading.
PTA longer PT indicates that it is taking longer time for the blood to clot. It could either mean liver dysfunction or vitamin K deficiency

What are the reference ranges for the enzymes tested under the LFT panel?

This table provides a rough picture of what should be the ideal range of different hepatic enzymes in an LFT report.

Liver Enzyme Normal reference range
ALT 3 – 40 iu/l
AST 3 – 30 iu/l
ALP 30 – 100 umol/l
GGT 8 – 60 u/l
LDH 140-280 u/L
Bilirubin 3 – 17 umol/l
Total protein6 – 8.3 g/dL
Albumin 35 – 50 g/l
PT 10-14 s/ 1

What is the cost of LFT in India?

The cost of a liver function test in India lies between Rs. 250 to 400, depending upon the city and the lab facilities available.

When can I get the results of the Liver Function Test?

The results can be obtained within a few hours at the earliest (if the testing is done on-site). At most, it will take 2-3 days for you to get the complete result.

How do doctors interpret the LFT results?

The right interpretation of the LFT results are usually done by a team of healthcare experts as the exact normal ranges for different enzymes varies from one case to another. What is normal for a particular individual depends on his overall health and other internal and lifestyle-associated factors such as age, alcohol consumption, pregnancy, diet, etc. LFT readings are not used to establish definite diagnoses but are rather treated as clues to what might be the issue with your liver. In addition to the absolute levels of these liver enzymes, their ratio w.r.t one another are also considered before coming down to any set conclusion.

Do I need to fast before an LFT?

In most cases, the doctor would advise you to fast for at least 8 hours prior to the blood sample collection for LFT. You are not supposed to consume anything other than water. However, this requirement might differ from one lab to another.

Should pregnant women undergo an LFT?

Yes, it is critical that pregnant women undergo this test to determine if the liver is functioning normally or not. It is normal for pregnant women to have slightly different values of liver enzymes that are measured via the LFT. But any deviation that exceeds the threshold level during gestation should be looked into immediately. During pregnancy, it has been observed that:

– ALP and albumin decrease
– ALT increases significantly with the gestational period
– AST, GGT, and bilirubin fluctuate slightly but remain well within the normal ranges

Can infants and children have abnormal LFT levels?

Yes, in fact, high levels of neonatal bilirubin is a common condition affecting millions of babies worldwide. Early detection of this enzyme can lower subsequent liver damage in newborn babies. Similarly, children can also acquire liver infections owing to contaminated food or water and may develop jaundice. In all these cases, an LFT test would be performed to determine the elevated levels of liver enzymes.

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