Health Encyclopedia

Haptoglobin

Definition

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.

How the test is performed

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore blood flow. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In an infant or young child:

The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

How to prepare for the test

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.

How the test will feel

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.

Why the test is performed

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.

Normal Values

The normal range is 27-139 mg/dL (milligrams per deciliter).

What abnormal results mean

Higher-than-normal levels may be due to:

Lower-than-normal levels may be due to:

What the risks are

Excessive bleeding
Fainting or feeling light-headed
Hematoma (blood accumulating under the skin)
Infection (a slight risk any time the skin is broken)
Multiple punctures to locate veins

References

McPherson RA and Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. Philadelphia, Pa: WB Saunders; 2007:237-8.

Review Date:3/8/2007
Reviewed By:Mark Levin, MD, Hematologist and Oncologist, Newark, NJ. Review provided by VeriMed Healthcare Network.

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