Haptoglobin

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Haptoglobin is a protein produced by the liver. It connects to a certain type of hemoglobin in the blood.

A blood test can tell how much haptoglobin you have in your blood.

Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

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Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

Your doctor may tell you to stop taking any drugs that can affect the test results.

Drugs that can raise haptoglobin levels include:

• Androgens
• Corticosteroids

Drugs that can lower haptoglobin levels include:

• Birth control pills
• Chlorpromazine
• Diphenhydramine
• Indomethacin
• Isoniazid
• Nitrofurantoin
• Quinidine
• Streptomycin

Never stop taking any medicine without first talking to your doctor.

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

This test is done to see how fast your red blood cells are destroyed. When red blood cells die, they release hemoglobin.

Haptoglobin attaches to this released hemoglobin, which is also called "free" hemoglobin. Free hemoglobin is not contained within red blood cells. The level of free hemoglobin is usually very low, but it rises whenever red blood cells are dying.

When the haptoglobin and hemoglobin attach, the new molecule goes to the liver, where parts of it (such as iron and amino acids) are recycled. The haptoglobin is destroyed.

When red blood cells are actively being destroyed, haptoglobin disappears faster than it is created. Thus, the levels of haptoglobin in the blood drop.

Review Date: 03/21/2010
Reviewed By: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; James R. Mason, MD, Oncologist, Director, Blood and Marrow Transplantation Program and Stem Cell Processing Lab, Scripps Clinic, Torrey Pines, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).