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Definition
This is a test that measures the amount of haptoglobin, a protein that binds free hemoglobin, in 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 circulation. 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
The health care provider may advise you to stop taking drugs that may affect the test (see "Special Considerations").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
Haptoglobin is measured to assess the rate at which your red blood cells are being destroyed. When red blood cells die, a process called hemolysis, they release their hemoglobin.
The liver produces haptoglobin and secretes it into the blood, where it finds and attaches to any "free" hemoglobin -- that is, hemoglobin not contained within red blood cells. The concentration of free hemoglobin is ordinarily very low, but the level rises whenever red blood cells are being destroyed.
After haptoglobin attaches to hemoglobin, the molecule goes to the liver where its components (iron, heme, and amino acids) are recycled. This process destroys the haptoglobin. When red blood cells are actively being destroyed, the rate of haptoglobin destruction by the liver will outpace the rate at which new haptoglobin is created. Thus, the levels of haptoglobin in the blood will decrease.
Normal Values
The normal range is 27-139 mg/dl (milligrams per deciliter)What abnormal results mean
Higher-than-normal levels may indicate:What the risks are
Special considerations
Haptoglobin levels may be affected by the presence of liver disease or kidney disease, extensive blood loss, and a variety of conditions that affect liver and kidney function.
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Page last updated: 28 October 2004 |