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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 the Test is Performed
A blood sample is needed. For information on how this is done see: VenipunctureHow 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 Results
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:
- Acute rheumatic disease
- Biliary obstruction
- Peptic ulcer
- Ulcerative colitis
- Other inflammatory conditions
Lower-than-normal levels may be due to:
- Chronic liver disease
- Drug-induced immune hemolytic anemia
- Erythroblastosis fetalis
- Hematoma
- Hemolytic anemia due to G6PD deficiency
- Idiopathic autoimmune hemolytic anemia
- Immune hemolytic anemia
- Primary liver disease
- Transfusion reaction
Risks
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. Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2008:chap 164.
Schwartz RS. Autoimmune and intravascular hemolytic anemias In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 163.
Reviewed By: Todd Gersten, MD, Hematology/Oncology, Palm Beach Cancer Institute, West Palm Beach, FL. Review provided by VeriMed Healthcare Network. Also reviewed by Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington; David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
