Liver Tests: What Do They Say About Your Health?

Your liver is a master at multitasking. It digests food, processes nutrients and removes toxins, and does away with old red blood cells, as well as hundreds of other important jobs.

When your liver isn’t working as it should, you can develop symptoms like:

• Jaundice.
• Nausea.
• Abdominal pain.
• Itching.
• Bruising.
• And more.

Why would my doctor order a liver function test?

There are certain symptoms that may cause your doctor to order a liver function test. They can also be an important part of your annual well-check.

“You may need liver tests to investigate jaundice, dark urine or pain in your right upper abdomen,” says hepatologist Carlos Romero-Marrero, MD. “But liver tests also are part of routine physical exams and can be used to monitor medications you’re taking.”

Liver function tests can reveal problems even before you have symptoms.

What are the different types of liver function tests?

Liver function tests are blood tests that measure substances in your blood to ensure your liver is functioning as it should. If your results are abnormal in any one of these tests, that doesn’t indicate a liver problem necessarily. Each of these tests is just one piece of the larger puzzle. Your doctor will consider your liver function test results along with any other tests, your overall health and any symptoms you are experiencing to determine whether your results point to any problems.

Alanine Transaminase Test (ALT test)

What is the ALT test?
The ALT test measures your levels of alanine transaminase (ALT), an enzyme in your liver. If your liver is damaged, ALT can leak into your blood.

What’s a good range for ALT test results?

• 10 to 40 units per liter is considered normal in adult men and people assigned male at birth.
• Four to 19 units per liter is considered normal in adult women and people assigned female at birth.

What could abnormal ALT results mean?

• Cirrhosis (scarred liver).
• Hepatitis (inflamed liver).
• Hemochromatosis (too much iron).
• Fatty liver disease.
• Liver tumor or cancer.
• Other liver disease.
• Mononucleosis.
• Drug use.
• Pancreatitis (inflamed pancreas).

Aspartate transaminase test (AST test)

What is the AST test?
The AST test measures levels of aspartate transaminase (AST), an enzyme in your liver and muscles. If your liver is damaged, AST can leak into your blood.

What is a good range for AST test results?

• 10 to 34 units per liter is considered normal in adults.

What could abnormal AST results mean?

• Cirrhosis (scarred liver).
• Hepatitis (inflamed liver).
• Hemochromatosis (too much iron).
• Liver tumor or cancer.
• Another liver disease.
• Mononucleosis.
• Drug use.
• Heart attack.
• Pancreatitis (inflamed pancreas).

“An abnormal ALT and/or AST that persists for more than six months should be investigated further,” Dr. Romero-Marrero says. “Your doctor may consider additional testing to check for viral, autoimmune and metabolic causes of liver disease. An abdominal ultrasound may also be ordered to check for the presence of fatty liver.”

Alkaline phosphatase test (ALP test)

What is the ALP test?

The ALP test measures your levels of alkaline phosphatase (ALP), an enzyme in your liver, bones, kidneys and digestive system. If your liver is damaged, ALP can leak into your blood.

What is a good range for ALP test results?

• 44 to 147 units per liter is considered normal in adults.

What could abnormal ALP results mean?

• Cirrhosis (scarred liver).
• Hepatitis (inflamed liver).
• A blocked bile duct.
• Mononucleosis.

If your ALP is high but your other liver tests are not, it could indicate:

• A bone disorder.
• Lymphoma.
• Heart failure.
• A bacterial infection

“As with elevated ALT and AST levels, your doctor will likely want to perform additional tests if you have elevated ALP levels for more than six months,” Dr. Romero-Marrero says. “An ultrasound of the liver is a common next step to check for obstructions, liver masses or problems related to the small bile ducts. Your doctor may also perform blood work to rule out other conditions.”

Gamma-glutamyl transpeptidase test (GGT test)

What is the GGT test?

The GGT test measures your levels of gamma-glutamyl transpeptidase (GGT), an enzyme in your liver, bile ducts and pancreas. If your liver is damaged or bile ducts are blocked, GGT can build up in your blood.

What is a good range for GGT test results?

• 0 to 30 units per liter is considered normal in adults.

What could abnormal GGT results mean?

• Alcohol use.
• Cirrhosis (scarred liver).
• Hepatitis (inflamed liver).
• Liver tumor or cancer.
• Other liver disease.
• Diabetes.
• Heart failure.
• Drug use.
• Disease of the lung or pancreas.

Globulin test

The globulin test measures your levels of globulins, which are proteins in your liver used to
fight infection and clot blood.

What is a good range for globulin test results?

• Serum globulin: 2.0 to 3.5 grams per deciliter is considered normal.
• Immunoglobulin M (IgM): 75 to 300 milligrams per deciliter is considered normal.
• Immunoglobulin G (IgG): 650 to 1,850 milligrams per deciliter is considered normal.
• Immunoglobulin A (IgA): 90 to 350 milligrams per deciliter is considered normal.

What could abnormal globulin test results mean?

Globulin levels that are lower than the normal range could indicate:

• Liver disease.
• Kidney disease.

Globulin levels that are higher than the normal range could indicate:

• Infection.
• Inflammatory disease.
• Immune disorder.
• Lymphoma or other cancer.

Albumin test

The albumin test measures your levels of albumin, a protein made in your liver that carries hormones and vitamins through your body.

What is a good range for albumin test results?

• 3.4 to 5.4 grams per deciliter is considered normal in adults.

What could low albumins test results mean?

• Cirrhosis (scarred liver).
• Hepatitis (inflamed liver).
• Other liver disease.
• Kidney disease.
• Intestinal disease.

Prothrombin test

The prothrombin test measures your levels of prothrombin, a protein made in your liver that helps clot your blood. A prothrombin time test measures how long it takes your blood to clot.

What is a good range for prothrombin test results?

• 0.8 to 1.1 international normalized ratio (INR) is considered normal, though higher levels can be normal if you’re taking blood-clotting medication.
• For the prothrombin time test, 11 to 13.5 seconds is considered normal.

What could high prothrombin test results mean?

• Liver disease.
• Bleeding disorder.
• Vitamin K deficiency.

Bilirubin test

The bilirubin test measures your levels of bilirubin, a yellow fluid in bile that is made when your red blood cells break down. If your liver is damaged, bilirubin can leak into your blood.

What is a good range for bilirubin test results?

• Direct (conjugated) bilirubin: Less than 0.3 milligrams per deciliter is considered normal.
• Total bilirubin: 0.1 to 1.2 milligrams per deciliter is considered normal.

What could abnormal bilirubin test results mean?

• Cirrhosis (scarred liver).
• Hepatitis (inflamed liver).
• Other liver disease.
• Gallbladder or bile duct disease. 

“Commonly, an isolated elevation of bilirubin related to a benign condition called Gilbert’s syndrome, which is caused by a less than efficient filtering or conjugation of bilirubin in some individuals,” Dr. Romero-Marrero says.

What do the results of these tests mean?

It’s important to remember that one abnormal test result doesn’t mean you have liver problems. Medication, diet and other factors can affect your scores.

“You may need liver tests to investigate jaundice, dark urine or pain in your right upper abdomen,” says Dr. Romero-Marrero. “But liver tests also are part of routine physical exams and can be used to monitor medications you’re taking.” Liver tests can reveal problems even before you have symptoms.

What puts you at risk for liver problems?

• Drinking too much alcohol.
• Hepatitis.
• Obesity.
• Diabetes.
• Family history of liver disease.

But, again, one abnormal test result doesn’t mean you have liver problems. Your doctor will look at a combination of scores to diagnose liver damage or disease and will explain any areas of concern and help you determine your next steps.