Haptoglobin

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”).

For infants and children:
The preparation you can provide for this test depends on your child’s age, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics:

     
  • infant test or procedure preparation (birth to 1 year)  
  • toddler test or procedure preparation (1 to 3 years)  
  • preschooler test or procedure preparation (3 to 6 years)  
  • schoolage test or procedure preparation (6 to 12 years)  
  • adolescent test or procedure preparation (12 to 18 years)

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:

     
  • acute rheumatic disease  
  • biliary obstruction  
  • peptic ulcer  
  • ulcerative colitis  
  • other inflammatory conditions

Lower-than-normal levels may indicate:

     
  • chronic liver disease  
  • erythroblastosis fetalis  
  • hematoma  
  • hemolytic anemias       o hemolytic anemia due to G6PD deficiency       o idiopathic autoimmune hemolytic anemia       o immune hemolytic anemia       o drug-induced immune hemolytic anemia  
  • primary liver disease  
  • transfusion reaction

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

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.

Drugs that can raise haptoglobin levels include androgens and corticosteroids

Drugs that can lower haptoglobin levels include birth control pills, chlorpromazine, diphenhydramine, indomethacin, isoniazid, nitrofurantoin, quinidine, and streptomycin.

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Johns Hopkins patient information

Last revised: December 4, 2012
by Janet G. Derge, M.D.

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