Name = PAGENAME
DiseasesDB = 12289
ICD10 = ICD10|D|58|0|d|55
ICD9 = ICD9|282.0
OMIM = 182900
OMIM_mul = OMIM2|270970
MedlinePlus = 000530
eMedicineSubj = med
eMedicineTopic = 2147
Spherocytosis is an auto-hemolytic
anemia(a disease of the blood) characterized by the production of red blood cells (RBCs), or "erythrocytes", that are sphere-shaped, rather than bi-concave disk shaped. It is caused by a molecular defect in one or more of the proteinsof the red blood cell cytoskeleton, including, spectrin, ankyrin, Band 3, or Protein 4.2. Because the cell skeleton has a defect, the blood cell contracts to its most surface-tension efficient and least flexible configuration, a sphere. The sphere-shaped red blood cells are known as spherocytes.
Though the spherocytes have a smaller surface area through which
oxygenand carbon dioxidecan be exchanged, they in themselves perform adequately to maintain healthy oxygen supplies. However, they have a high osmotic fragility--when placed into water, they are more likely to burst than normal red blood cells. These cells are more prone to physical degradation. They are most commonly found in immunologically-mediated hemolytic anemias and in hereditary spherocytosis, but the former would have a positive direct Coombs test and the latter would not. The misshapen but otherwise healthy red blood cells are mistaken by the spleenfor old or damaged red blood cells and it thus constantly breaks them down, causing a cycle whereby the body destroys its own blood supply (auto- hemolysis).
spleen's hemolysisresults directly in varying degrees of anemiaand hyperbilirubinemia, which in turn result in symptoms of fatigue, pallor, and jaundice.
Acute cases can threaten hypoxemia through
anemiaand acute kernicterusthrough hyperbilirubinemia, particularly in newborns.
Chronic symptoms include
anemiaand splenomegaly, a potentially life-threatening enlargement of the spleendue to its increased activity. Furthermore, the detritus of the broken-down blood cells-- bilirubin--accumulates in the gallbladder, and can cause pigmented gallstonesor "sludge" to develop. In chronic patients, an infectionor other illness can cause an increase in the destruction of red blood cells, resulting in the appearance of acute symptoms, a "hemolytic crisis".
peripheral blood smears, many of the red blood cells will appear abnormally small and will lack the central pallor--the lighter area in the middle of an RBC as seen under a microscope.
The CBC (cell blood count) laboratory values will show elevated
The splenic cords are congested with red blood cells to be destroyed and
macrophages of the spleen will show signs of actively destroying erythrocytes (erythrophagocytosis). This will result in an elevated bilirubinlevel.
bone marrowin its role of manufacturing red blood cells will display hyperplasia, the increased activity of replacing RBCs. As a result, immature red blood cell--or reticulocyte--counts will appear elevated.
Treatment of acute symptoms
Acute symptoms of
anemiaand hyperbilirubinemia can indicate treatment with blood transfusions or exchanges. Transfusions treat anemiaby adding healthy donor blood to the patient's own, providing needed red blood cells. As the transfused blood does not contain spherocytes, it will not be hemolysed per se, but the overactive spleen may still break down a significant proportion of the transfused blood. Exchanges treat hyperbilirubinemia by replacing some portion of the patient's blood with healthy donor blood, thus removing some portion of the toxic bilirubin.
Treatment of chronic symptoms
Chronic symptoms of
anemiaand splenomegalytypically indicate dietary supplementation of folic acid and eventual treatment by splenectomy, the surgical removal of the spleen.
In longstanding cases in which patients have taken supplemental
ironor received numerous blood transfusions, iron overloadmay be a significant problem, being a potential cause of cardiomyopathyand liver disease. If there is iron overload, chelation therapywith agents such as desferrioxaminemay be necessary.
splenectomydoes not affect the shape of the blood cells, it does remove the more obvious physical symptomsof the disorder, as the blood cells are no longer constantly broken down. Though it offers near-immediate relief from symptoms, splenectomy is often not performed until the patient is in late childhood, so as not to hinder the patient's ability to fight off childhood infections. The surgeryis often performed laparoscopically. Given that surgery is preplanned, it is highly recommended that patients receive prior Pneumovax-II pneumococcus, conjugated-C meningococcus& Haemophilus influenzae type b vaccinationsto combat the patient's new lower tolerance against overwhelming post-splenectomy infection. The Pneumovax needs repeating every six years and the patient should have a yearly influenza vaccine. Prophylactic antibioticsare also given. (See aspleniafor further details on these measures).
Treatment of the disorder
Both measures described above treat the symptoms, not the cause of the disorder. Non-hereditary spherocytosis has several causes, each treated differently. Experimental
gene therapyexists to treat hereditary spherocytosisin lab mice; however, this treatment has not yet been tried on humans and because of the risks involved in human gene therapy, it may never be. See also Hereditary spherocytosis.
Red blood cells
* [http://www.healthsystem.virginia.edu/internet/hematology/HessEDD/Redbloodcelldisorders/spherocyte.cfm Spherocytes] : Presented by the University of Virginia
* [http://my.webmd.com/hw/anemia/nord81.asp A short article from WebMD]
* [http://www.nlm.nih.gov/medlineplus/ency/imagepages/1220.htm A picture of spherocytes from Medline]
* [http://www.emedicine.com/med/topic2147.htm A detailed and technical (but good) article from eMedicine]
* Kumar, Vinay, Abul Abbas, and Nelson Fausto. "Robbins and Cotran Pathologic Basis of Disease, 7th edition (2004)."
* Schneider, Arthur S. and Philip A. Stanzo. "Board Review Series: Pathology, 2nd edition (2002)."
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