Liver function tests (LFTs or LFs), also referred to as a hepatic panel, are groups of blood tests that provide information about the state of a patient’s liver. These tests include prothrombin time (PT/INR), activated Partial Thromboplastin Time (aPTT), albumin, bilirubin (direct and indirect), and others. The liver transaminases aspartate transaminase (AST or SGOT) and alanine transaminase (ALT or SGPT) are useful biomarkers of liver injury in a patient with some degree of intact liver function.^[rx]^[rx]^[rx] Most liver diseases cause only mild symptoms initially, but these diseases must be detected early. Hepatic (liver) involvement in some diseases can be of crucial importance. This testing is performed on a patient’s blood sample. Some tests are associated with functionality (e.g., albumin), some with cellular integrity (e.g., transaminase), and some with conditions linked to the biliary tract (gamma-glutamyl transferase and alkaline phosphatase). Because some of these tests do not measure function, it is more accurate to call these liver chemistries or liver tests rather than liver function tests.^[rx] Several biochemical tests are useful in the evaluation and management of patients with hepatic dysfunction. These tests can be used to detect the presence of liver disease, distinguish among different types of liver disorders, gauge the extent of known liver damage, and monitor the response to treatment. Some or all of these measurements are also carried out (usually about twice a year for routine cases) on those individuals taking certain medications, such as anticonvulsants, to ensure that the medications are not adversely impacting the person’s liver.

Liver function tests are common tests that are used to see how well the liver is working. Tests include:

Albumin
Alpha-1 antitrypsin
Alkaline phosphatase ( ALP )
Alanine aminotransferase ( ALT )
Aspartate aminotransferase ( AST )
Gamma-glutamyl transpeptidase (GGT)
5′ nucleotidase
Prothrombin time, also expressed as an international normalized ratio (INR)
Serum bilirubin
Urine bilirubin

Albumin – blood (serum) test

Albumin is a protein made by the liver. A serum albumin test measures the amount of this protein in the clear liquid portion of the blood.

Albumin can also be measured in the urine.

How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

The health care provider may tell you to temporarily stop taking certain medicines that can affect the test. Drugs that can increase albumin levels include:

Anabolic steroids
Androgens
Growth hormone
Insulin

Do not stop taking any of your medicines without talking to your provider first.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging.

Afterward, there may be some throbbing or a slight bruise. This soon goes away.

Why the Test is Performed

Albumin helps move many small molecules through the blood, including bilirubin, calcium, progesterone, and medicines. It plays an important role in keeping the fluid from the blood from leaking out into the tissues.

This test can help determine if a patient has liver disease or kidney disease, or if the body is not absorbing enough protein.

Normal Results

The normal range is 3.4 to 5.4 g/dL.

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.

What Abnormal Results Mean

A lower-than-normal level of blood albumin may be a sign of:

Kidney diseases
Liver disease (for example, hepatitis , or cirrhosis that may cause ascites )

Decreased blood albumin may occur when your body does not get or absorb enough nutrients, such as with:

After weight-loss surgery
Crohn disease
Low-protein diets
Celiac disease
Whipple disease

Increased blood albumin may be due to:

Dehydration
High protein diet
Having a tourniquet on for a long time when giving a blood sample

Other conditions for which the test may be performed:

Burns (widespread)
Wilson disease

If you are receiving large amounts of intravenous fluids, the result of this test may be inaccurate.

Albumin will be decreased during pregnancy.

Risks

There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight, but may include:

Bleeding from where the needle was inserted
Fainting or feeling lightheaded
Hematoma (blood collecting under the skin)
Infection (rare)

Alpha-1 antitrypsin blood test

A1AT test

Alpha-1 antitrypsin is a laboratory test to measure the amount of alpha-1 antitrypsin (A1AT) in your blood.

How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

There is no special preparation.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.

Why the Test is Performed

This test is helpful in identifying a rare form of emphysema in adults and a rare form of liver disease (cirrhosis) in children and adults caused by an A1AT deficiency . A1AT deficiency is passed down through families. The condition causes the liver to make too little of a protein that protects the lungs and liver from damage.

Everyone has two copies of the gene that makes A1AT. Most people with a lower-than-normal level of A1AT have one normal gene for A1AT, and one abnormal gene. People with two abnormal copies of the gene have more severe disease.

Normal Results

Normal value ranges may vary slightly among different laboratories. Talk to your health care provider about the meaning of your specific test results.

What Abnormal Results Mean

A lower-than-normal level of A1AT may be associated with:

Damage of the large airways in the lungs ( bronchiectasis )
Scarring of the liver ( cirrhosis )
Chronic obstructive pulmonary disease (COPD)
Liver tumors
Yellowing of the skin and eyes due to blocked bile flow ( obstructive jaundice )
High blood pressure in the large vein leads to the liver (portal hypertension )

Risks

There is very little risk involved with having your blood taken. Veins and arteries vary in size from one person to another, and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight, but may include:

Excessive bleeding
Fainting or feeling lightheaded
Hematoma (blood accumulating under the skin)
Infection (a slight risk any time the skin is broken)

ALP – blood test

Alkaline phosphatase

Alkaline phosphatase (ALP) is a protein found in all body tissues. Tissues with higher amounts of ALP include the liver, bile ducts, and bone.

A blood test can be done to measure the level of ALP.

A related test is the ALP isoenzyme test .

How the Test is Performed

A blood sample is needed. Most of the time blood is drawn from a vein located on the inside of the elbow or the back of the hand.

How to Prepare for the Test

You should not to eat or drink anything for 6 hours before the test, unless your health care provider tells you otherwise.

Many medicines can interfere with blood test results.

Your provider will tell you if you need to stop taking any medicines before you have this test.
DO NOT stop or change your medicines without talking to your provider first.

How the Test will Feel

You may feel slight pain or a sting when the needle is inserted. You may also feel some throbbing at the site after the blood is drawn.

Why the Test is Performed

Reasons the test may be done include:

To diagnose liver or bone disease
To check, if treatments for those diseases are working
As part of a routine liver function test

Normal Results

The normal range is 44 to 147 IU/L (international units per liter) or 0.73 to 2.45 microkat/L.

Normal values may vary slightly from laboratory to laboratory. They also can vary with age and gender. High levels of ALP are normally seen in children undergoing growth spurts and in pregnant women.

The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

What Abnormal Results Mean

Abnormal results may be due to the following conditions:

Higher-than-normal ALP levels

Biliary obstruction
Bone conditions
Osteoblastic bone tumors , osteomalacia , a fracture that is healing
Liver disease or hepatitis
Eating a fatty meal if you have blood type O or B
Hyperparathyroidism
Leukemia
Lymphoma
Paget disease
Rickets
Sarcoidosis

Lower-than-normal ALP levels

Hypophosphatasia
Malnutrition
Protein deficiency
Wilson disease

Other conditions for which the test may be done:

Alcoholic liver disease (hepatitis/cirrhosis)
Alcoholism
Biliary stricture
Gallstones
Giant cell (temporal, cranial) arteritis
Multiple endocrine neoplasia (MEN) II
Pancreatitis
Renal cell carcinoma

Alanine transaminase (ALT) blood test

SGPT; Serum glutamate pyruvate transaminase; Alanine transaminase; Alanine aminotransferase

The alanine transaminase (ALT) blood test measures the level of the enzyme ALT in the blood.

How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

No special preparation is needed.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.

Why the Test is Performed

ALT is an enzyme found in a high level in the liver. Injury to the liver results in release of ALT into the blood.

This test is used to determine if a person has liver damage.

Normal Results

The normal range is:

Male: 10 to 40 U/L
Female: 7 to 35 U/L

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different samples. Talk to your health care provider about the meaning of your specific test results.

What Abnormal Results Mean

An increased ALT level is usually a sign of liver disease. Liver disease is even more likely when the levels of substances checked by other liver blood tests have also increased.

An increased ALT level may be due to any of the following:

Scarring of the liver ( cirrhosis )
Death of liver tissue
Swollen and inflamed liver ( hepatitis )
Too much iron in the body ( hemochromatosis )
Too much fat in the liver (fatty liver)
Lack of blood flow to the liver (liver ischemia)
Liver tumor or cancer
Use of drugs that are toxic to the liver
Mononucleosis (“mono”)
Swollen and inflamed pancreas (pancreatitis)

Risks

Other risks associated with having blood drawn are slight, but may include:

Bleeding from where the needle was inserted
Fainting or feeling lightheaded
Hematoma (blood collecting under the skin)
Infection (rare)

Aspartate aminotransferase (AST) blood test

Aspartate aminotransferase; Serum glutamic-oxaloacetic transaminase; SGOT

The aspartate aminotransferase (AST) blood test measures the level of the enzyme AST in the blood.

How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

No special preparation is needed.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.

Why the Test is Performed

AST is an enzyme found in high levels in the liver, heart, and muscles. It is also found in lesser amounts in other tissues. An enzyme is a protein that causes a specific chemical change in the body.

This test is mainly done along with other tests (such as ALT , ALP , and bilirubin ) to diagnose and monitor liver disease .

Normal Results

The normal range is 10 to 34 U/L.

What Abnormal Results Mean

An increased AST level is usually a sign of liver disease. Liver disease is even more likely when the levels of substances checked by other liver blood tests have also increased.

An increased AST level may be due to any of the following:

Scarring of the liver ( cirrhosis )
Death of liver tissue
Heart attack
Too much iron in the body ( hemochromatosis )
Swollen and inflamed liver ( hepatitis )
Lack of blood flow to the liver (liver ischemia)
Liver cancer or tumor
Use of drugs that are toxic to the liver
Mononucleosis (“mono”)
Muscle disease or trauma
Swollen and inflamed pancreas ( pancreatitis )

AST level may also increase after:

Burns (deep)
Heart procedures
Seizure
Surgery

Pregnancy and exercise may also cause an increased AST level.

Risks

Veins vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Risks associated with having blood drawn are slight, but may include:

Bleeding from where the needle was inserted
Fainting or feeling lightheaded
Hematoma (blood collecting under the skin)
Infection (a slight risk any time the skin is broken)

Gamma-glutamyl transpeptidase (GGT) blood test

Gamma-GT; GGTP; GGT

The gamma-glutamyl transpeptidase (GGT) blood test measures the level of the enzyme GGT in the blood.

How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

The health care provider may tell you to stop taking medicines that can affect the test.

Drugs that can increase GGT level include:

Alcohol
Phenytoin
Phenobarbital

Drugs that can decrease GGT level include:

Birth control pills
Clofibrate

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.

Why the Test is Performed

GGT is an enzyme found in high level in the liver, kidney, pancreas, heart, and brain. It is also found in lesser amount in other tissues. An enzyme is a protein that causes a specific chemical change in the body.

This test is used to detect diseases of the liver or bile ducts. It is also done with other tests (such as the ALT , AST , ALP , and bilirubin tests) to tell the difference between liver or bile duct disorders and bone disease.

It may also be done to screen for or monitor alcohol use.

Normal Results

The normal range for adults is 8 to 65 U/L.

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different specimens. Talk to your provider about the meaning of your specific test results.

What Abnormal Results Mean

An increased GGT level may be due to any of the following:

Alcohol use
Diabetes
Flow of bile from the liver is blocked ( cholestasis )
Heart failure
Swollen and inflamed liver ( hepatitis )
Lack of blood flow to the liver
Death of liver tissue
Liver cancer or tumor
Lung disease
Pancreas disease
Scarring of the liver ( cirrhosis )
Use of drugs that are toxic to the liver

Risks

Other risks associated with having blood drawn are slight but may include:

Bleeding from where the needle was inserted
Fainting or feeling lightheaded
Hematoma (blood collecting under the skin)
Infection (rare)

Prothrombin time (PT)

PT; Pro-time; Anticoagulant-prothrombin time; Clotting time: protime; INR; International normalized ratio

Prothrombin time (PT) is a blood test that measures the time it takes for the liquid portion (plasma) of your blood to clot.

A related blood test is partial thromboplastin time (PTT) .

How the Test is Performed

A blood sample is needed . If you are taking ant blood-thinning medicines, you will be watched for signs of bleeding.

How to Prepare for the Test

Certain medicines can change blood test results.

Your health care provider will tell you if you need to stop taking any medicines before you have this test. This may include aspirin, heparin, antihistamines, and vitamin C.
DO NOT stop or change your medicines without talking to your doctor first.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or slight bruising. This soon goes away.

Why the Test is Performed

The most common reason to perform this test is to monitor your levels when you are taking a blood-thinning medicine called warfarin. You are likely taking this medicine to prevent blood clots.

Your provider will check your PT regularly.

You may also need this test to:

Find the cause of abnormal bleeding or bruising
Check how well your liver is working
Look for signs of a blood clotting or bleeding disorder

Normal Results

PT is measured in seconds. Most of the time, results are given as what is called INR (international normalized ratio).

If you are not taking blood thinning medicines, such as warfarin, the normal range for your PT results is:

11 to 13.5 seconds
INR of 0.8 to 1.1

If you are taking warfarin to prevent blood clots, your doctor will most likely choose to keep your INR between 2.0 and 3.0.

Ask your doctor what result is right for you.

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results

What Abnormal Results Mean

If you are not taking blood thinning medicines, such as warfarin, an INR result above 1.1 means your blood is clotting more slowly than normal. This may be due to:

Bleeding disorders , a group of conditions in which there is a problem with the body’s blood clotting process.
Disorder in which the proteins that control blood clotting become over active ( disseminated intravascular coagulation )
Liver disease
Low level of vitamin K

If you are taking warfarin to prevent clots your doctor will most likely choose to keep your INR between 2.0 and 3.0:

Depending on why you are taking the blood thinner, the desired level may be different.
Even when your INR stays between 2.0 and 3.0, you are more likely to have bleeding problems.
INR results higher than 3.0 may put you at even higher risk for bleeding.
INR results lower than 2.0 may put you at risk for developing a blood clot.

A PT result that is too high or too low in someone who is taking warfarin (Coumadin) may be due to:

The wrong dose of medicine
Drinking alcohol
Taking certain over-the-counter (OTC) medicines, vitamins, supplements, cold medicines, antibiotics, or other medicines
Eating food that changes the way the blood-thinning medicine works in your body

Your provider will teach you about taking warfarin (Coumadin) the proper way.

Risks

This test is often done on people who may have bleeding problems. Their risk of bleeding is slightly higher than for people without bleeding problems.

Other slight risks can include:

Fainting or feeling lightheaded
Hematoma (blood accumulating under the skin)
Infection (a slight risk any time the skin is broken)
Multiple punctures to locate veins

Bilirubin blood test

Total bilirubin – blood; Unconjugated bilirubin – blood; Indirect bilirubin – blood; Conjugated bilirubin – blood; Direct bilirubin – blood

The bilirubin blood test measures the level of bilirubin in the blood. Bilirubin is a yellowish pigment found in bile, a fluid made by the liver.

Bilirubin can also be measured with a urine test .

How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

You should not eat or drink for at least 4 hours before the test. Your health care provider may instruct you to stop taking medicines that affect the test.

Many drugs may change the bilirubin level in your blood. Make sure your provider knows which medicines you are taking.

Why the Test is Performed

A small amount of older red blood cells are replaced by new blood cells every day. Bilirubin is left after these older blood cells are removed. The liver helps break down bilirubin so that it can be removed from the body in the stool.

A high level of bilirubin in the blood can lead to jaundice . Jaundice is a yellow color in the skin, mucus membranes, or eyes.

Jaundice is the most common reason to check bilirubin level. The test will likely be ordered when:

The provider is concerned about a newborn’s jaundice (most newborns have some jaundice)
Jaundice develops in older infants, children, and adults

A bilirubin test is also ordered when the provider suspects a person has liver or gallbladder problems.

Normal Results

It is normal to have some bilirubin in the blood. A normal level is:

Direct (also called conjugated) bilirubin: 0 to 0.3 mg/dL
Total bilirubin: 0.3 to 1.9 mg/dL

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different samples. Talk to your provider about the meaning of your specific test results.

What Abnormal Results Mean

In newborns, bilirubin level is higher for the first few days of life. Your child’s provider must consider the following when deciding whether your baby’s bilirubin level is too high:

How fast the level has been rising
Whether the baby was born early
The baby’s age

Jaundice can also occur when more red blood cells than normal are broken down. This can be caused by:

A blood disorder called erythroblastosis fetalis
A red blood cell disorder called hemolytic anemia
Transfusion reaction in which red blood cells that were given in a transfusion are destroyed by the person’s immune system

The following liver problems may also cause jaundice or a high bilirubin level:

Scarring of the liver ( cirrhosis )
Swollen and inflamed liver ( hepatitis )
Other liver disease
Disorder in which bilirubin is not processed normally by the liver ( Gilbert disease )

The following problems with gallbladder or bile ducts may cause higher bilirubin levels:

Abnormal narrowing of the common bile duct ( biliary stricture )
Cancer of the pancreas or gallbladder
Gallstones

Bilirubin – urine

Conjugated bilirubin – urine; Direct bilirubin – urine

Bilirubin is a yellowish pigment found in bile , a fluid produced by the liver.

This article is about a lab test to measure the amount of bilirubin in the urine. Large amounts of bilirubin in the body can lead to jaundice.

Bilirubin may also be measured with a blood test.

How the Test is Performed

This test can be done on any urine sample.

For an infant, thoroughly wash the area where urine exits the body.

Open a urine collection bag (a plastic bag with an adhesive paper on one end).
For males, place the entire penis in the bag and attach the adhesive to the skin.
For females, place the bag over the labia.
Diaper as usual over the secured bag.

This procedure may take a few tries. An active baby can move the bag causing urine to go into the diaper.

Check the infant often and change the bag after the infant has urinated into it. Drain the urine from the bag into the container provided by your health care provider.

Deliver the sample to the laboratory or to your provider as soon as possible.

How to Prepare for the Test

Many medicines can interfere with blood test results.

Your provider will tell you if you need to stop taking any medicines before you have this test.
DO NOT stop or change your medicines without first talking to your provider.

How the Test will Feel

The test involves only normal urination, and there is no discomfort.

Why the Test is Performed

This test may be done to diagnose liver or gallbladder problems.

Normal Results

Bilirubin is not normally found in the urine.

What Abnormal Results Mean

Increased levels of bilirubin in the urine may be due to:

Biliary tract disease
Cirrhosis
Gallstones in the biliary tract
Hepatitis
Liver disease
Tumors of the liver or gallbladder

Considerations

Bilirubin can break down in light. That is why babies with jaundice are sometimes placed under blue fluorescent lamps.