A haptoglobin test is a blood test that measures your haptoglobin levels. Haptoglobin is a protein that your liver produces. Haptoglobin binds with circulating or free hemoglobin, a protein found in your red blood cells. Haptoglobin transports free hemoglobin that has been released from red blood cells back to the liver for recycling.
Haptoglobin testing can help diagnose a form of anemia called hemolytic anemia. Hemolytic anemia occurs when a disease destroys red blood cells or causes them to die prematurely.
Haptoglobin testing is performed to measure the rate at which your red blood cells die. When red blood cells die, they release hemoglobin, the protein that attaches to haptoglobin. The released hemoglobin is called “free hemoglobin.”
The combined molecules of free hemoglobin and haptoglobin travel to the liver. Your liver takes the nutrients that you need, such as iron and amino acids, and recycles them.
According to the National Institutes of Health (NIH), everyone has some free hemoglobin and haptoglobin in their blood. Anemia elevates your hemoglobin levels because more red blood cells are dying. At the same time, your haptoglobin levels drop. This is because the substance is being eliminated from your body faster than your liver can make it (NIH, 2012).
Normal haptoglobin levels range from 45 to 165 milligrams of haptoglobin per deciliter of blood (mg/dL). Levels lower than 45 mg/dL can indicate that your red blood cells are dying off more quickly than normal.
Your doctor may decide to run a haptoglobin test if you exhibit signs of hemolytic anemia. With hemolytic anemia, your bone marrow cannot keep up with the demand to make new red blood cells. The inadequate supply of red blood cells means that your body may not get enough oxygen.
Symptoms of hemolytic anemia may include:
- severe fatigue
- cold hands and feet
- dizziness or lightheadedness
- shortness of breath
- arrhythmia (an abnormal heartbeat)
You may also experience abdominal pain and jaundice. Jaundice is the yellowing of the skin and the whites of your eyes. Both of these symptoms are the result of high bilirubin levels. Bilirubin forms when free hemoglobin is released into your bloodstream and breaks down. Higher-than-normal bilirubin levels often cause jaundice and may result in gallstones (hard deposits in the gallbladder), which can cause stomach pain.
You will have your blood drawn in a doctor’s office or clinical laboratory. You do not need to fast prior to the haptoglobin test. A technician will swab the inside of your elbow with alcohol or another sterilizing agent. He or she will insert a needle into the vein in the inside of your arm to draw blood. After removing the needle from your arm, the technician will bandage the insertion site.
A haptoglobin blood test takes just a few minutes. Your doctor will receive the results within a few days.
Results of the test vary from lab to lab. Your healthcare provider will discuss your individual results with you.
Your results may be affected by underlying medical conditions or medications you take. Your haptoglobin levels could be elevated if you have recently had a heart attack or suffer from ulcerative colitis or rheumatic diseases, such as rheumatoid arthritis. Your levels may also be high if you take corticosteroids or androgen drugs to treat other medical conditions.
Androgen drugs (steroids) are sometimes used:
- by bodybuilders and athletes to build muscle
- to treat certain types of cancer
- as hormone replacement for men who have had their testicles removed
Corticosteroids are used to treat inflammation such as rheumatoid arthritis, systemic vasculitis (inflammation of the blood vessels), and other disorders.
Your haptoglobin levels could be lower-than-normal if you use birth control pills or the antibiotic streptomycin. Chronic liver disease can also cause your haptoglobin levels to drop. Discuss your health history and medication use with your primary care physician to help him or her interpret your haptoglobin test accurately.
Anemia is a likely diagnosis if your haptoglobin levels and red blood cell count are both low. The red blood cell count is a laboratory test used to identify the number of red blood cells in your blood. It is performed on a blood sample and is usually part of a complete blood count (CBC), a test that identifies the number and health of different types of cells found in your blood.