What is a haptoglobin (HP) test?
This test measures the amount of haptoglobin in the blood. Haptoglobin is a protein made by your liver. It attaches to a certain type of hemoglobin. Hemoglobin is a protein in your red blood cells that carries oxygen from your lungs to the rest of your body. Most hemoglobin is located inside red blood cells, but small amounts circulate in the bloodstream. Haptoglobin binds to hemoglobin in the bloodstream. Together, the two proteins are known as the haptoglobin-hemoglobin complex. This complex is quickly cleared from the bloodstream and removed from the body by your liver.
When red blood cells are damaged, they release more hemoglobin into the bloodstream. That means more of the haptoglobin-hemoglobin complex will be cleared from the body. The haptoglobin may leave the body faster than the 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 anemia. These include:
- Pale skin
- Shortness of breath
- Rapid heart rate
- 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. The test may be done 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?
If your results show that your haptoglobin levels are lower than normal, it may mean you have one of the following conditions:
- Hemolytic anemia
- Liver disease
- Reaction to a transfusion
Your health care 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 health care provider.
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. But haptoglobin testing is not usually used to diagnose or monitor conditions related to high haptoglobin levels.
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