How the Test is Performed
A blood sample is needed.
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a bruise. This soon goes away.
Why the Test is Performed
This test is done to tell if a person has abnormal hemoglobin that causes sickle cell disease and sickle cell trait. Hemoglobin is a protein in red blood cells that carries oxygen.
In sickle cell disease, a person has two abnormal hemoglobin S genes. A person with sickle cell trait has only one of these abnormal genes and no symptoms, or only mild ones.
This test does not tell the difference between these two conditions. Another test, called hemoglobin electrophoresis, will be done.
A negative test result is normal.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.
What Abnormal Results Mean
- Sickle cell anemia
- Sickle cell trait
Iron deficiency or blood transfusions within the past 3 months can cause a false negative result.
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.
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)
Sickledex; Hgb S test
Steinberg MH. Sickle cell disease and associated hemoglobinopathies. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 166.
Vajpayee N, Graham SS, Bern S. Basic examination of blood and bone marrow. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 30.
Update Date 2/24/2014
Updated by: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.