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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 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 41 - 165 mg/dL (milligrams per deciliter).

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

What abnormal results mean

Higher-than-normal levels may be due to:

Lower-than-normal levels may be due to:

What the risks are

There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

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

References

Yee DL, Bollard CM, Geaghan SM. Appendix: Normal Blood Values: Selected Reference Values for Neonatal, Pediatric, And Adult Populations. In: Hoffman R, Benz EJ, Shattil SS, et al, eds. . 5th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2008:chap 164.

Schwartz RS. Autoimmune and intravascular hemolytic anemias In: Goldman L, Schafer AI, eds. . 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 163.

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    Encyclopedia content is provided as information only and not intended to replace the advice and instruction from your personal physician.