At a Glance

Why Get Tested?

To decide if you have sickle prison cell trait or sickle prison cell disease

When To Get Tested?

Routinely equally part of newborn screening; if you are in a loftier gamble group and were born before newborn screening was mandated and want to know if yous have sickle jail cell disease or are carrying the sickle cell trait; when you accept signs and symptoms of anemia or aberrant results from a complete blood count (CBC) and your health care practitioner suspects sickle cell disease or trait

Sample Required?

A blood sample drawn from a vein in your arm or, for infants, by pricking a heel or finger

Exam Training Needed?

None; however, if this examination is used for diagnosis, the sample should not be fatigued after a recent blood transfusion.

What is being tested?

Sickle prison cell anemia is an inherited disorder that leads to the production of an abnormal type of hemoglobin chosen hemoglobin S (Hb Due south or Hgb Southward). Sickle cell tests decide the presence and relative amount of hemoglobin S in a blood sample or detect mutations in the genes that produce hemoglobin to help diagnose sickle prison cell anemia and/or identify people with sickle cell trait.

Hemoglobin is the protein in red blood cells (RBCs) that binds to oxygen in the lungs and carries it to tissues throughout the body. Typically, hemoglobin A (Hb A,adult hemoglobin) makes upwards most of the hemoglobin found in normal RBCs in adults, with small amounts of hemoglobin A2 and hemoglobin F. Before babies are born, they normally produce large amounts of hemoglobin F (Hb F,fetal hemoglobin), which is so replaced by Hb A equally the predominant hemoglobin shortly later on birth.

Sickle cell disease is an inherited condition, passed from parents to children. Inheriting mutations in the genes that code for the product of hemoglobin can lead to abnormal types of hemoglobin (variants), such as Hb S and hemoglobin C (Hb C). Hemoglobin Cis 1 of the more common hemoglobin variants and may cause no symptoms or balmy illness.

  • Sickle cell disease and anemia—a person who inherits ii abnormal gene copies (alleles), i of which is a Hb S gene, has sickle cell illness (i.due east., a person who has one Hb S factor copy and one Hb C gene copy has sickle jail cell disease.) A person who inherits two Hb South gene copies (one from each parent; homozygous) has sickle cell anemia, the most common and serious for of sickle cell disease.
  • Sickle cell trait (carrier)—a person who inherits one normal hemoglobin factor re-create from one parent and a Hb Due south gene copy from the other parent (heterozygous) has sickle prison cell trait and is a sickle cell carrier. Carriers generally don't experience signs and symptoms associate with sickle cell disease simply tin can laissez passer the mutation to their children.

Hb South can form crystals that change the shape of the RBC from a round disc to a characteristic sickle shape. This contradistinct shape limits the RBC'due south ability to period smoothly throughout the blood vessels in the body, limits the hemoglobin'south power to transport oxygen to tissues, and decreases RBC lifespan from 120 days to about ten-20 days. A person with sickle prison cell affliction (homozygous for Hb S) can become severely anemic because the trunk cannot produce RBCs as fast equally they are destroyed. The affected person can endure painful episodes and a variety of complications when sickled cells get lodged in and obstruct small claret vessels.

Common Questions

How is it used?

Sickle cell tests may be used to screen for or help diagnose sickle cell anemia (as well called sickle prison cell affliction) or to identify individuals who are genetic carriers and have sickle cell trait. Testing may be used for:

  • Newborn screening—All states require that newborns be screened for sickle cell anemia, as well as some other hemoglobin disorders.
  • Carrier screening—It is recommended that all pregnant women or those considering pregnancy receive data regarding carrier screening for hemoglobin disorders, including sickle cell disease. Carrier screening lets prospective parents know whether they each are carriers and are at hazard of passing on 2 defective gene copies, one from each them, to whatever children who and so would exist affected by the disease.
  • General screening—to identify sickle jail cell trait in asymptomatic parents who have an affected child or in other family members of an individual who has sickle cell trait or sickle jail cell disease. Screening may also exist done for those who were not screened at nascency because universal newborn testing was not yet implemented.
  • Diagnosis—to detect and/or identify sickle prison cell disease in those with a positive screening test or symptoms of unexplained anemia or abnormal results on a complete blood count (CBC)

Several types of sickle cell tests are available and multiple tests may exist required. The types of examination used depend on the purpose of testing.

  • Hemoglobin S solubility examination and sodium metabisulfite test— these tests may exist used for screening individuals half dozen months one-time or older. They are not diagnostic and are not used for newborn screening. The tests detect the presence of hemoglobin Due south but do not distinguish between sickle prison cell affliction and trait.
  • Hemoglobinopathy (Hb) evaluation—several kinds of tests are bachelor for evaluating the type and relative amounts of various normal and abnormal hemoglobins. These methods typically separate the different types of hemoglobin that are present and so that they can exist identified and measured. They may be used for screening, diagnosis and/or monitoring. Examples include:
    • Hemoglobin electrophoresis
    • Hemoglobin fractionation by HPLC
    • Isoelectric focusing
    • Mass spectrometry
    • Capillary zone–In people diagnosed with sickle cell disease, these tests may be used to measure the relative amount of Hb Southward and follow it over the form of treatment. For example, testing may be done after a blood transfusion or erythrocytapheresis/cherry cell exchange to ensure that the hemoglobin South level has been reduced. In addition, treatment with the drug hydroxyurea should result in a decrease in Hb S and an increase in fetal hemoglobin (Hb F), and so these tests can exist used to monitor how well someone is responding to therapy.
  • Genetic testing (Deoxyribonucleic acid assay)—this tests for mutations in the genes that produce hemoglobin components. It can determine whether someone has 1 or two factor copies (alleles) of the Hb Due south mutation or has two unlike mutations in hemoglobin genes (e.g., Hb S and Hb C). Genetic testing can be used for carrier testing and for diagnosis. For significant women, amniotic fluid may be tested at 14 to 16 weeks to provide a diagnosis.  It can also be performed earlier with chorionic villus sampling. Sometimes, testing may exist done past analyzing prison cell-free fetal DNA in the female parent's blood.
  • Occasionally, a specialized testing called Dna sequencing may be done to help identify less common hemoglobin disorders. Genetic counseling and educational activity should be provided so that patients understand test results, implications of the results, and their adventure of passing genetic disorders to any children.

Other tests that may be used to assist evaluate someone who is suspected of having or who is known to accept sickle cell trait or illness include:

  • Complete claret count (CBC)—among other things, the CBC indicates the number of red blood cells too as the amount of hemoglobin and volition evaluate the size and shape of the RBCs present. This test is used to detect anemia.
  • Blood smear (likewise chosen peripheral smear and manual differential)—a trained laboratorian looks at a thin, stained layer of claret on a slide under a microscope. The number and type of red claret cells are evaluated to see if they are normal. Sickle-shaped RBCs may exist seen on the claret smear.
  • Iron studies—these tests mensurate different aspects of the body'south atomic number 26 storage and usage. They are ordered to assistance make up one's mind whether someone has an iron deficiency anemia or an excess amount of fe (iron overload). People with sickle jail cell anemia who receive multiple blood transfusions may experience iron overload.

When is it ordered?

Sickle prison cell tests are routinely ordered shortly later birth to screen newborns for sickle jail cell anemia.

Testing may be done when those who were born before newborn screening was mandated desire to know if they have sickle cell affliction or are carrying the sickle jail cell trait, especially if they are in a high-risk grouping. In African Americans, sickle cell illness occurs in ane out of every 365 births.

Carrier screening may be offered when a adult female is significant or considering pregnancy. If a adult female is found to be a carrier for sickle cell, testing should be offered to her partner.  Sickle cell tests may too be ordered when a person has abnormal results on a complete claret count (CBC) and blood smear and/or has signs and symptoms that suggest the presence of sickle jail cell anemia.

Examples of signs, symptoms and complications of sickle cell anemia include:

  • Pain due to sickle cell crisis—the most common symptoms of sickle cell disease are episodes of pain that tin last for extended periods of time. The pain tin can occur throughout the body and often involves the bones, joints, lungs, and tummy.
  • Anemia—sickle prison cell disease is a hemolytic anemia, meaning that the aberrant, sickled RBCs pause down (hemolyze) more chop-chop than normal red blood cells and cannot be replaced by the body every bit quickly as needed. This leads to a decreased number of RBCs and reduced ability of the RBCs to send oxygen throughout the trunk.
  • Increased number and frequency of infections, especially pneumonia, which is the leading cause of death in children with sickle cell disease.
  • Coughing, chest pain, and fever suspected to exist acquired by a serious complexity of sickle cell disease called acute chest syndrome.

What does the test result mean?

Newborn screening
In newborns who deport the sickle cell factor re-create, nearly of the hemoglobin is fetal hemoglobin F, just a small-scale amount of hemoglobin Due south will also be present. If a newborn has sickle cell trait, there may be a minor corporeality of hemoglobin A and hemoglobin S. A full diagnostic evaluation should exist done following positive screening results.

Hemoglobin S solubility test and sodium metabisulfite screening
Some hemoglobin S will be present in those who deport 1 sickle jail cell gene (sickle cell trait) and much more will exist present in those who have sickle cell affliction.

Diagnostic testing
Adults with sickle jail cell trait will produce mostly normal hemoglobin A, while those with sickle cell disease (anemia) volition produce mostly Hb Due south with no Hb A. People who have two cistron copies for two different hemoglobin variants will ordinarily produce varying amounts of both types. For example, they may produce both Hb S and Hb C but no Hb A.

Genetic testing
If 2 copies of the Hb S cistron mutation are detected, then the person has sickle cell disease. If the person has one cistron that codes for Hb South and ane normal gene, then the person has sickle cell trait. If the person has one Hb S copy and a Hb C or beta thalassemia mutation, then the person is likely to experience some symptoms and complications associated with sickle cell disease. If the person has one Hb S cistron copy and another, more rare hemoglobin variant, and then the person may or may not have any symptoms or complications.

Some examples of results that may exist seen with sickle cell testing are listed in the following tabular array.

Results Seen Status Genes
Slightly decreased Hb A; Moderate amount Hb Due south (about twoscore%) Sickle cell trait Ane gene re-create for Hb S (heterozygous)
Majority Hb Southward; Increased Hb F (up to ten%); No Hb A Sickle cell disease Two gene copies for Hb S (homozygous)

Is there anything else I should know?

Sickle cell anemia symptoms and the complications experienced volition vary profoundly from person to person, fifty-fifty within the aforementioned family.

Recent claret transfusions, typically inside the concluding iii months of the appointment of testing, may cause a imitation-negative examination result with some of the tests (east.g., Hb S solubility tests) because transfusion of normal RBCs reduce the relative amount of hemoglobin S present in an affected person'south system.

People with sickle jail cell trait are mostly salubrious, but those who exercise heavily, such as athletes and those who are exposed to aridity or altitude extremes, may sometimes experience sickle cell anemia symptoms. Sickle cell carriers produce both Hb A and some Hb S. When they are subjected to meaning stresses that reduce the amount of oxygen in the body, the RBCs that incorporate Hb South can sickle.

Who is at risk for sickle cell disease?

Anyone tin can inherit Hb South cistron mutations, but sickle cell disease is more prevalent amid those of African ancestry and those who tin can trace their roots to the Mediterranean area, South and Fundamental America, the Heart Due east, India, and the Caribbean area.

Why is this design of prevalence seen?

It mirrors the areas of the earth where malaria is institute. Historically, sickle prison cell offered some protection and survival advantage against malaria. Since people from these areas have moved throughout the world, sickle cell gene mutations have become more widespread. A 2013 study noted that the rates of sickle prison cell anemia are increasing worldwide and are projected to touch more than than 400,000 newborns by 2050, with Bharat and sub-Saharan Africa showing the sharpest increases.

Why would an athlete be tested for sickle cell trait?

Newborn screening identifies almost cases of sickle cell trait and sickle cell anemia. However, this screening was non universally performed in the U.S. until relatively recently. Many adults, and peculiarly athletes born in other countries, may not have been tested to determine their sickle cell status. Since there is some gamble of "exertional sickling" during intense grooming, the National Collegiate Athletic Association (NCAA) advocates testing higher athletes who have not documented their sickle prison cell status.

Why would Dna sequencing be washed as role of sickle cell testing?

Your health intendance practitioner may asking that Deoxyribonucleic acid sequencing be done to assistance decide the types of abnormal hemoglobin that may be nowadays. It is not routine testing merely may be necessary if it is suspected that you have a less common form of hemoglobin (variant), such as hemoglobin F. Rather than testing for i specific gene mutation, DNA sequencing determines the order of Dna building blocks (nucleotides) in a person'south genetic code. This method may exist used to help identify hemoglobin disorders caused by less common mutations.

Related Content

View Sources

Sources Used in Electric current Review

Hemoglobin S, Screen, Blood Clinical Information. Mayo Clinic, Mayo Medical Laboratories. Bachelor online at http://world wide web.mayomedicallaboratories.com/interpretive-guide/?blastoff=H&unit_code=9180. Accessed January 2017.

Lichtin, A.E. (2013 October). Sickle jail cell illness. Merck Manual Professional Version. Available online at http://www.merckmanuals.com/professional/hematology-and-oncology/anemias-caused-past-hemolysis/sickle-prison cell-disease. Accessed January 2017.

Gersten, T. (Updated 2016 February 1). Sickle cell anemia. MedlinePlus Medical Encyclopedia. Available online at http://world wide web.nlm.nih.gov/medlineplus/ency/article/000527.htm. Accessed January 2017.

Gersten, T. (Updated 2016 February xi). Sickle jail cell exam. MedlinePlus Medical Encyclopedia. Available online at http://www.nlm.nih.gov/medlineplus/ency/commodity/003666.htm. Accessed January 2017.

(Updated 2016 Baronial 31). Sickle cell disease. Centers for Illness Command and Prevention. Bachelor online at http://www.cdc.gov/ncbddd/sicklecell/treatments.html. Accessed January 2017.

Maakaron, J.Due east. (Updated 2016 October 3). Sickle cell anemia workup. Medscape. Bachelor online at http://emedicine.medscape.com/article/205926-workup. Accessed January 2017.

Mayo Clinic Staff. (2016 December 29). Sickle cell anemia. Diagnosis. Available online at http://www.mayoclinic.org/diseases-weather/sickle-cell-anemia/diagnosis-treatment/diagnosis/dxc-20303501. Accessed Jan 2017.

(Updated January 2017). Hemoglobinopathies. Arup Consult. Available online at https://arupconsult.com/content/hemoglobinopathies?tab=tab_item-2. Accessed January 2017.

Sources Used in Previous Reviews

(2006 May). What is Sickle Cell Anemia. National Heart, Lung and Claret Institute Information Heart [On-line information]. Bachelor online at http://www.nhlbi.nih.gov/health/dci/Diseases/Sca/SCA_WhatIs.html.

Bender, Grand.A. (2006 March 7, Updated). Sickle Prison cell Disease. GeneReviews [On-line data]. Available online through http://www.genetests.org.

(© 2006). Hemoglobin Evaluation. ARUP's Guide to Clinical Laboratory Testing [On-line information]. Bachelor online at http://www.aruplab.com/guides/clt/tests/clt_a307.jsp#1150784.

(2004). Interpretation of Newborn Hemoglobin Screening Results. Michigan Department of Community Health [On-line information]. Bachelor online through http://world wide web.michigan.gov.

(2004 August). Sickle Prison cell Disease. March of Dimes, Quick Reference Fact Sheets [On-line information]. Available online at http://www.marchofdimes.com/professionals/681_1221.asp.

Raj, A. and Bertolone, S. (Updated 2009 July 9). Sickle Cell Anemia. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/commodity/958614-overview. Accessed September 2009.

Bender, M. A. and Hobbs, W. (Updated 2009 August vi). Sickle Jail cell Disease GeneReviews [On-line information]. Available online at http://world wide web.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=gene∂=sickle. Accessed September 2009.

Hildreth, C. et. al. (2008 Dec x). Sickle Cell Vasculopathy. JAMA. 2008;300(22):2690 [On-line data]. PDF available for download at http://jama.ama-assn.org/cgi/reprint/300/22/2690.pdf. Accessed September 2009.

Mayo Clinic Staff (2009 April i). Sickle jail cell anemia. MayoClinic.com [On-line information]. Bachelor online at http://www.mayoclinic.com/health/sickle-prison cell-anemia/DS00324/METHOD=impress. Accessed September 2009.

(2008 February). Sickle Prison cell Affliction. March of Dimes Fact Sheets [On-line information]. Bachelor online at http://www.marchofdimes.com/professionals/14332_1221.asp. Accessed September 2009.

(Reviewed 2009 June nine). Sickle Prison cell Disease: 10 Things You lot Need to Know. CDC [On-line information]. Bachelor online at http://www.cdc.gov/Features/Sicklecell/. Accessed September 2009.

(2008 August). Sickle Cell Anemia. National Heart, Lung, and Blood Found [On-line data]. Available online at http://www.nhlbi.nih.gov/health/dci/Diseases/Sca/SCA_WhatIs.html. Accessed September 2009.

Pagana, 1000. D. & Pagana, T. J. (© 2007). Mosby'south Diagnostic and Laboratory Test Reference eighth Edition: Mosby, Inc., Saint Louis, MO. Pp 523-525.

Clarke, Due west. and Dufour, D. R., Editors (© 2006). Contemporary Practice in Clinical Chemistry: AACC Press, Washington, DC. Pp 219-223.

Wu, A. (© 2006). Tietz Clinical Guide to Laboratory Tests, 4th Edition: Saunders Elsevier, St. Louis, MO. Pp 518-521.

(October five, 2009) National Guideline Clearinghouse. Screening for sickle jail cell disease in newborns: U.Southward. Preventive Services Task Force recommendation statement. Available online at http://www.guideline.gov/summary/summary.aspx?doc_id=11371&nbr=005908&string=sickle+AND+cell+AND+anemia. Accessed October 2009.

Sickle Cell Anemia. (Updated February. 7, 2012). MedlinePlus Medical Encyclopedia. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000527.htm. Accessed Baronial 2013.

Sickle Cell Illness. (Updated Sept. xv, 2011). Centers for Disease Control and Prevention. Available online at http://www.cdc.gov/ncbddd/sicklecell/treatments.html. Accessed Baronial 2013.

Sickle Prison cell Test. (Updated Feb. 28, 2011). MedlinePlus Medical Encyclopedia. Bachelor online at http://www.nlm.nih.gov/medlineplus/ency/article/003666.htm. Accessed Baronial 2013.

Sickle prison cell anemia on rise in newborns worldwide. (Published July 16, 2013). U.S. News and World Written report Online. Available at http://health.usnews.com/wellness-news/news/articles/2013/07/sixteen/sickle-cell-anemia-on-rising-in-newborns-worldwide. Accessed Baronial 2013.

Ask a Laboratory Scientist

Ask a Laboratory Scientist

This form enables patients to ask specific questions about lab tests. Your questions will be answered by a laboratory scientist as part of a voluntary service provided by one of our partners, American Order for Clinical Laboratory Science. Please permit ii-iii business days for an email response from one of the volunteers on the Consumer Information Response Team.

Send Us Your Question