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| | __NOTOC__ |
| | For Patient Information page click [[Hereditary spherocytosis (patient information)|here]] |
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| {{DiseaseDisorder infobox | | | {{DiseaseDisorder infobox | |
| Name = Spherocytosis | | | Name = Spherocytosis | |
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| {{Spherocytosis}} | | {{Spherocytosis}} |
| {{CMG}} | | {{CMG}} |
| __NOTOC__
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| | == [[Spherocytosis overview|Overview]] == |
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| ==Overview== | | == [[Spherocytosis historical perspective|Historical Perspective]]== |
| '''Spherocytosis''' is an auto-[[hemolysis|hemolytic]] [[anemia]] (a [[blood diseases|disease of the blood]]) characterized by the production of [[red blood cell]]s (RBCs), or ''erythrocytes'', that are sphere-shaped, rather than donut-shaped or, more specifically, bi-concave disk shaped. It is caused by a molecular defect in one or more of the [[proteins]] of the red blood cell [[cytoskeleton]] (usually ''[[ankyrin]]'', sometimes ''[[spectrin]]''). Because the cell skeleton has a defect, the blood cell contracts to its most surface-tension efficient and least flexible configuration, a sphere, rather than the more flexible donut-shape. The sphere-shaped red blood cells are known as '''spherocytes'''.
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| Though the spherocytes have a smaller surface area through which [[oxygen]] and [[carbon dioxide]] can be exchanged, they in themselves perform adequately to maintain healthy oxygen supplies. However, they have a high [[osmosis|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 anemia]]s and in [[hereditary spherocytosis]], but the former would have a positive [[Coombs test#Direct Coombs test|direct Coombs test]] and the latter would not. The misshapen but otherwise healthy red blood cells are mistaken by the [[spleen]] for 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]]).
| | == [[Spherocytosis classification|Classification]] == |
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| ==Symptoms== | | == [[Spherocytosis pathophysiology|Pathophysiology]] == |
| The [[spleen]]'s [[hemolysis]] results directly in varying degrees of [[anemia]] and hyperbilirubinemia, which in turn result in symptoms of [[Fatigue (physical)|fatigue]], [[pallor]], and [[jaundice]].
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| Acute cases can threaten [[Hypoxia (medical)|hypoxemia]] through [[anemia]] and acute [[kernicterus]] through hyperbilirubinemia, particularly in newborns.
| | == [[Spherocytosis causes|Causes]] == |
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| Chronic symptoms include [[anemia]] and [[splenomegaly]], or enlargement of the [[spleen]] due to its [[hypersplenism|increased activity]]. In some cases the spleen continues to change sizes. Yet in other cases the spleen just continues growing which puts the patient at a greater risk for rupture, which can cause death. Furthermore, the detritus of the broken-down blood cells--[[bilirubin]]--accumulates in the [[gallbladder]], and can cause [[gallstones]] or "sludge" to develop. In chronic patients, an [[infection]] or other illness can cause an increase in the destruction of red blood cells, resulting in the appearance of acute symptoms, a ''hemolytic crisis''.
| | == [[Spherocytosis differential diagnosis|Differentiating Spherocytosis from other Diseases]] == |
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| ==Diagnosis== | | == [[Spherocytosis epidemiology and demographics|Epidemiology and Demographics]]== |
| In [[peripheral blood smear]]s, many of the [[red blood cell]]s will appear abnormally small and will lack the central pallor--the lighter area in the middle of a RBC as seen under a [[microscope]].
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| The CBC (cell blood count) laboratory values will show elevated MCHC.
| | == [[Spherocytosis risk factors|Risk Factors]] == |
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| The [[spleen|splenic cords]] are congested with red blood cells to be destroyed and [[macrophage]]s of the spleen will show signs of actively destroying erythrocytes (erythrophagocytosis). This will result in an elevated [[bilirubin]] level.
| | == [[Spherocytosis natural history, complications and prognosis|Natural History, Complications and Prognosis]] == |
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| The [[bone marrow]] in 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.
| | == Diagnosis == |
| | [[Spherocytosis history and symptoms|History and Symptoms]] | [[Spherocytosis physical examination|Physical Examination]] | [[Spherocytosis laboratory findings|Laboratory Findings]] | [[Spherocytosis CT|CT]] | [[Spherocytosis MRI|MRI]] | [[Spherocytosis ultrasound|Ultrasound]] | [[Spherocytosis other imaging findings|Other Imaging Studies]] | [[Spherocytosis other diagnostic studies|Other Diagnostic Studies]] |
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| ===Pathology=== | | == Treatment == |
| [[Image:Spherocytosis.jpg|thumb|left|Spherocytosis<ref>http://picasaweb.google.com/mcmumbi/USMLEIIImages</ref>]]
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| ==Treatment==
| | [[Spherocytosis medical therapy|Medical Therapy]] | [[Spherocytosis surgery|Surgery]] | [[Spherocytosis prevention|Prevention]] | [[Spherocytosis cost-effectiveness of therapy | Cost Effectiveness of Therapy]] | [[Spherocytosis future or investigational therapies|Future or Investigational Therapies]] |
| ===Treatment of acute symptoms===
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| Acute symptoms of [[anemia]] and hyperbilirubinemia can indicate treatment with '''[[blood transfusion]]s or exchanges'''. Transfusions treat [[anemia]] by adding healthy donor blood to the patient's own, providing needed [[red blood cells]]. As the transfused blood does not contain elliptocytes, 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]].
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| ===Treatment of chronic symptoms=== | | ==Case Studies== |
| Chronic symptoms of [[anemia]] and [[splenomegaly]] typically indicate '''dietary supplementation of [[iron]]''' and eventual treatment by '''[[splenectomy]]''', the surgical removal of the [[spleen]].
| | :[[Spherocytosis case study one|Case #1]] |
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| Iron supplementation supports the increased production of red blood cells, but in longstanding cases in which patients have taken supplemental [[iron]] or received numerous [[blood transfusion]]s, [[iron overload]] may be a significant problem, being a potential cause of [[cardiomyopathy]] and [[liver disease]]. If there is [[iron overload]], [[chelation therapy]] with agents such as desferrioxamine may be necessary.
| | ==Related Chapters== |
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| While [[splenectomy]] does not affect the shape of the blood cells, it does remove the more obvious physical [[symptoms]] of 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 [[infection]]s. Currently<!-- "recent years" in 2007 -->, the [[surgery]] is often performed [[Laparoscopic surgery|laparoscopically]]; this results in a shorter recovery time and a much smaller [[scar]]. Given that surgery is preplanned, it is highly recommended that patients receive prior Pneumovax-II [[pneumococcus]], conjugated-C [[meningococcus]] & Haemophilus influenzae type b vaccinations to 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 [[flu vaccine]]. [[Prophylactic]] [[antibiotics]] are also given. (See [[asplenia]] for further details on these measures).
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| ===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 therapy]] exists to treat [[hereditary spherocytosis]] in 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]].
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| ==See also==
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| * [[Hereditary spherocytosis]] | | * [[Hereditary spherocytosis]] |
| * [[Anemia]] | | * [[Anemia]] |
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| * [[Blood diseases]] | | * [[Blood diseases]] |
| * [[Red blood cells]] | | * [[Red blood cells]] |
| * Hereditary diseases
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| ==External links== | | ==External links== |
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| *[http://www.nlm.nih.gov/medlineplus/ency/imagepages/1220.htm A picture of spherocytes from Medline] | | *[http://www.nlm.nih.gov/medlineplus/ency/imagepages/1220.htm A picture of spherocytes from Medline] |
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| ==References==
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| * Kumar, Vinay, Abul Abbas, and Nelson Fausto. "Robbins and Cotran Pathologic Basis of Disease, 7th edition (2004)."
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| * Schneider, Arthur S. and Philip A. Stanzo. "Board Review Series: Pathology, 2nd edition (2002)."
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