What is a haptoglobin (HP) test?

This test measures the amount of haptoglobin in your blood. Haptoglobin is a protein made by your liver to get rid of the hemoglobin outside your red blood cells.

Hemoglobin is a protein in your red blood cells that carries oxygen from your lungs to the rest of your body. Most hemoglobin is found inside your red blood cells. When red blood cells die, they release hemoglobin. This results in small amounts of hemoglobin circulating in your bloodstream. Haptoglobin binds to the hemoglobin in your bloodstream, and then your liver removes it from the body.

Damaged red blood cells also release hemoglobin. So if your red blood cells are damaged or break down faster than usual, you will have more hemoglobin than usual in your bloodstream. That means haptoglobin will bind to all of this extra hemoglobin so that it can be cleared from your body. The haptoglobin may leave the body faster than your liver can make it. This causes your haptoglobin blood levels to drop. If your haptoglobin levels are too low, it may be a sign of a disorder of the red blood cells, such as anemia.

Other names: hemoglobin-binding protein, HPT, Hp

What is it used for?

A haptoglobin test is most often used to diagnose hemolytic anemia. Hemolytic anemia is a disorder that happens when your red blood cells are destroyed faster than they can be replaced. This test may also be used to see if another type of anemia or another blood disorder is causing your symptoms.

Why do I need a haptoglobin test?

You may need this test if you have symptoms of hemolytic anemia or another blood disorder. These may include:

• Weakness or fatigue
• Pale skin
• Shortness of breath
• Headache
• Dizziness
• Arrhythmia (a problem with the rate or rhythm of your heartbeat)
• Jaundice, a condition that causes your skin and eyes to turn yellow
• Dark colored urine

You may also need this test if you've had a blood transfusion. A haptoglobin test may be done along with another test called direct anti-globulin. The results of these tests can show if you've had a bad reaction to the transfusion.

What happens during a haptoglobin test?

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

Will I need to do anything to prepare for the test?

You don't need any special preparations for a haptoglobin test.

Are there any risks to a haptoglobin test?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

What do the results mean?

A low haptoglobin level is normal for infants less than six months old.

Otherwise, a haptoglobin level that is lower than normal may be a sign of:

• Hemolytic anemia
• Liver disease
• Reaction to a transfusion

A haptoglobin level that is higher than normal may be a sign of:

• Ulcerative colitis
• Acute rheumatic disease, such as arthritis or other conditions that affect the joints, bones, and muscles
• A severe infection
• Diabetes

Your provider may order other blood tests to help make a diagnosis. These include:

• Reticulocyte Count
• Hemoglobin Test
• Hematocrit Test
• Lactate Dehydrogenase Test
• Blood Smear
• Complete Blood Count

These tests may be done at the same time or after your haptoglobin test.

If you have questions about your results, talk to your provider. Tell your provider if you are taking any medicines. Some medicines may cause your haptoglobin test results to be higher or lower than normal.

To understand the results of a haptoglobin test, your provider will consider your symptoms, medical history, and the results of other blood tests.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about a haptoglobin test?

High haptoglobin levels may be a sign of an inflammatory disease. Inflammatory diseases are disorders of the immune system that can cause serious health problems. However, haptoglobin testing is not usually used to diagnose or monitor conditions related to high haptoglobin levels.

Severe blood loss and conditions that worsen your kidney function may also affect haptoglobin level results.