Liver Function Test

Jai Ganesh · Yesterday 18:57:48

Liver Function Test

Gist

Liver function tests (LFTs) are blood tests that measure enzymes, proteins, and substances produced or processed by the liver to assess its overall health, screen for infections (hepatitis), and monitor damage or disease. They commonly measure ALT, AST, ALP, bilirubin, and albumin. Elevated levels often indicate liver inflammation, damage, or bile duct issues.

Liver function tests (also called a liver panel) use a sample of your blood to measure several substances made by your liver.

The most common liver function tests measure:

* Albumin, a protein made in the liver.
* Total protein. This test measures the total amount of protein in your blood, which includes albumin and globulins. These proteins are mainly made in your liver.
* ALP (alkaline phosphatase), ALT (alanine transaminase), AST (aspartate aminotransferase), and GGT (gamma-glutamyl transferase). These are enzymes that are mainly made in your liver. Enzymes are proteins that speed up certain chemical reactions in your body.
* Bilirubin, a waste product your body makes when it breaks down old red blood cells. Your liver removes most of the bilirubin from your body.
* Lactate dehydrogenase (LDH), an enzyme found in most of the tissues in your body, but some of the largest amounts are found in your liver.
* Prothrombin time (PT), how long it takes your blood to clot. Prothrombin is a protein involved in blood clotting. It's made in your liver.

Some of these tests can show how well your liver is working and others can show whether your liver may be damaged by liver disease or injury. But liver function tests alone usually can't diagnose specific diseases. So, if your results are abnormal, you'll usually need other tests to find the exact cause.

Summary

Liver function tests are blood tests used to help find the cause of your symptoms and monitor liver disease or damage. The tests measure the levels of certain enzymes and proteins in your blood.

Some of these tests measure how well the liver is performing its regular functions of producing protein and clearing bilirubin, a blood waste product. Other liver function tests measure enzymes that liver cells release in response to damage or disease.

Irregular liver function test results don't always mean liver disease. A member of your health care team will typically explain your results and what they mean.

Why it's done

Liver function tests can be used to:

* Screen for liver infections, such as hepatitis.
* Monitor a disease, such as viral or alcoholic hepatitis, and determine how well a treatment is working.
* Look for signs of serious disease, particularly scarring of the liver, called cirrhosis.
* Monitor possible side effects of medicines.

Liver function tests check the levels of certain enzymes and proteins in your blood. Levels that are higher or lower than usual can mean liver problems. The pattern and degree of elevation of these tests along with the overall clinical picture can provide hints to the underlying cause of these problems.

Some common liver function tests include:

* Alanine transaminase (ALT). ALT is an enzyme found in the liver that helps convert proteins into energy for the liver cells. When the liver is damaged, ALT is released into the bloodstream and levels increase. This test is sometimes referred to as SGPT.
* Aspartate transaminase (AST). AST is an enzyme that helps the body break down amino acids. Like ALT, AST is usually present in blood at low levels. An increase in AST levels may mean liver damage, liver disease or muscle damage. This test is sometimes referred to as SGOT.
* Alkaline phosphatase (ALP). ALP is an enzyme found in the liver and bone and is important for breaking down proteins. Higher-than-usual levels of ALP may mean liver damage or disease, such as a blocked bile duct, or certain bone diseases, as this enzyme is also present in bones.
* Albumin and total protein. Albumin is one of several proteins made in the liver. Your body needs these proteins to fight infections and to perform other functions. Lower-than-usual levels of albumin and total protein may mean liver damage or disease. These low levels also can be seen in other gastrointestinal and kidney-related conditions.
* Bilirubin. Bilirubin is a substance produced during the breakdown of red blood cells. Bilirubin passes through the liver and is excreted in stool. Higher levels of bilirubin might mean liver damage or disease. At times, conditions such as a blockage of the liver ducts or certain types of anemia also can lead to elevated bilirubin.
* Gamma-glutamyltransferase (GGT). GGT is an enzyme in the blood. Higher-than-usual levels may mean liver or bile duct damage. This test is nonspecific and may be elevated in conditions other than liver disease.
* L-lactate dehydrogenase (LD). LD is an enzyme found in the liver. Higher levels may mean liver damage. However, other conditions also may cause higher levels of LD.
* Prothrombin time (PT). PT is the time it takes your blood to clot. Increased PT may mean liver damage. However, it also can be higher if you're taking certain blood-thinning drugs, such as warfarin.

Details

Liver function tests are blood tests that measure different substances produced by your liver, including proteins, enzymes and bilirubin. High or low levels of different substances can indicate different diseases.

Overview:

What are liver function tests?

Liver function tests are blood tests that measure different substances produced by your liver. These measurements give your healthcare provider important information about the overall health of your liver and how well it’s working. A liver panel will often measure several substances in one blood sample. It may include various enzymes, proteins and byproducts.

What are the five primary liver function tests?

The most common liver tests include:

* Liver enzymes test. Your liver enzymes include alkaline phosphatase (ALP), alanine transaminase (ALT), aspartate aminotransferase (AST) and gamma-glutamyl transferase * (GGT). These are elevated when there’s liver injury.
* Total protein test.A total protein test measures levels of protein in your blood. Your liver makes protein, and low protein levels may indicate that your liver isn’t functioning optimally.
* Bilirubin test. Bilirubin is a waste product that your liver deposits in bile.
* LDH test. Lactate dehydrogenase (LDH) is an enzyme found in many of your body’s tissues, including your liver.
* Prothrombin Time (PT) test. This test measures how long it takes for a sample of your blood to clot, a process that involves proteins that your liver produces.

These tests are all part of a routine blood panel called a comprehensive metabolic panel.

When are tests done to check liver function?

Your healthcare provider might want to check these values to screen you for possible hepatitis or other liver diseases. If they already know that you have liver disease, they might want to check how it’s progressing or whether a treatment is working. You may also have a liver test to monitor the side effects of certain medications that are known to affect your liver.

What kinds of things can a liver panel tell you?

Different values and ratios of different substances may tell your healthcare provider:

* If you have liver inflammation (hepatitis).
* Whether the inflammation is alcohol-related or nonalcoholic (metabolic).
* Whether you have a problem in your liver itself or in your bile ducts.
* If your liver function is impaired, and if so, how much.
* If your bile flow is impaired, and if so, how much.
* Whether your medications are affecting your liver, and if so, how much.

Test Details:

How do liver function tests work?

A healthcare provider draws a small amount of blood from a vein in your arm to test in the lab. They’ll look for abnormally high or low levels of different substances. Often, they’ll want to compare levels of different enzymes or proteins to each other. If the balance is off, that can help them understand better what may be going on in your liver.

What happens during the test?

You may have the test at a hospital or a specialized testing facility. Your healthcare technician will locate the vein in your arm that they’ll use to draw blood from and then clean the site. They may wrap your arm with a compression band to make your veins stick out. They’ll insert a small needle into your vein and draw blood into a vial. It only takes a few minutes.

What happens after?

Your technician will send your blood sample to a lab for analysis. The lab may be in the same facility or a different one. This may determine how fast your results come back. It may be a few hours or a few days. As long as you aren’t feeling lightheaded from the blood draw, you can go home now, resume your medications and have something to eat and drink.

Additional Information

* Liver function tests (LFTs) are blood tests that check how well your liver is working.
* They measure proteins, enzymes and other substances in your blood.
* LFTs can help find liver disease and liver problems, check their severity and monitor treatment.
* If your test results are abnormal, your doctor may recommend more tests.

Discuss the results of your LFT blood test with your doctor to understand what they mean for you.

What are liver function tests?

Liver function tests (LFTs) are common blood tests that check how well your liver is working. They measure different proteins, enzymes and other substances in your blood.

These tests help:

* find liver disease and liver problems
* check how severe any problems are
* track how well treatment is working

Your liver is a large organ in your abdomen. It helps your body by filtering harmful substances and breaking down medicines and alcohol. It also supports digestion, makes bile and produces important proteins and enzymes.

Liver function tests are also called hepatic function tests.

Different liver function tests

There are several liver function tests, including:

* alanine aminotransferase (ALT) — an enzyme that shows liver cell health
* albumin — a protein made by the liver that helps regulate fluids
* alkaline phosphatase (ALP) — an enzyme linked to bile flow and bone health, as well as made by the placenta during pregnancy
* aspartate aminotransferase (AST) — an enzyme that can indicate liver damage
* bilirubin — a substance that reflects bile production and excretion
* gamma glutamyl transferase (GGT) — an enzyme that can indicate liver stress
* total protein — the total amount of proteins in the blood, including albumin and globulins

What are proteins and enzymes?

Proteins are important building blocks in your body. Some proteins, such as albumin and globulins, help move nutrients, fight infections and balance fluids.

Enzymes are special proteins that speed up chemical reactions in your body. Liver enzymes, such as ALT and AST help break down substances and can show if your liver is damaged.

When are liver function tests used?

Your doctor may refer you for liver function tests to check for liver problems and monitor your liver health, especially if you:

* have or may have a liver condition or liver disease
* have or may have cirrhosis of the liver
* have or may have a hepatitis virus infection
* have signs of a biliary obstruction — a blockage in the bile ducts that stops bile from draining properly into your gut
* drink a lot of alcohol
* have a family history of liver disease
* take medicines that can affect your liver function

Your doctor might refer you for LFTs if you have symptoms such as:

* jaundice (yellowing of the skin or eyes)
* dark urine (wee) or light-coloured faeces (math)
* nausea and vomiting
* abdominal (tummy) pain or swelling
* itching

Where can I get a liver function test?

You usually need to go to a pathology collection centre with a referral from your doctor. Your doctor will recommend one near you.

Sometimes, your doctor will collect blood for testing in their clinic. Blood tests are also routinely done in hospitals.

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Liver Function Test

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