Editing Autosplenectomy

{{Short description|Loss of function of the spleen}}
An '''autosplenectomy''' (from'' 'auto-' ''self,'' '-splen-' ''spleen,'' '[[List of -ectomies|-ectomy]]' ''removal) is a negative outcome of disease and occurs when a [[disease]] damages the [[spleen]] to such an extent that it becomes shrunken and non-functional.<ref>[http://library.med.utah.edu/WebPath/HEMEHTML/HEME116.html "Autosplenectomy" with sickle cell anemia, gross] at [http://library.med.utah.edu/WebPath/ WebPath], The Internet Pathology Laboratory for Medical Education at Mercer University School of Medicine. Retrieved September 10, 2011</ref> The spleen is an important immunological organ that acts as a filter for [[red blood cell]]s, triggers [[phagocytosis]] of invaders, and mounts an immunological response when necessary.<ref name="Brousse 165–176">{{Cite journal|title = The spleen and sickle cell disease: the sick(led) spleen|journal = British Journal of Haematology|date = 2014-07-01|issn = 1365-2141|pages = 165–176|volume = 166|issue = 2|doi = 10.1111/bjh.12950|language = en|first1 = Valentine|last1 = Brousse|first2 = Pierre|last2 = Buffet|first3 = David|last3 = Rees|pmid=24862308|s2cid = 40448991|doi-access = free}}</ref> Lack of a spleen, called [[asplenia]], can occur by autosplenectomy or the surgical counterpart, [[splenectomy]]. Asplenia can increase susceptibility to infection.<ref>{{Cite web|url = http://www.mayoclinic.org/tests-procedures/splenectomy/basics/risks/prc-20014837|title = Splenectomy Risks - Mayo Clinic|website = www.mayoclinic.org|access-date = 2016-03-02}}</ref>  Autosplenectomy can occur in cases of [[sickle-cell disease]] where the misshapen cells block blood flow to the spleen, causing [[fibrosis|scarring]] and eventual [[atrophy]] of the organ.<ref name="Brousse 165–176"/> Autosplenectomy is a rare condition that is linked to certain diseases but is not a common occurrence. It is also seen in [[systemic lupus erythematosus]] (SLE).

==Consequences==
{{Main article|Asplenia}}
Absence of effective splenic function or absence of the whole spleen ([[asplenia]]) is associated with increased risks of [[overwhelming post-splenectomy infection]], especially from [[polysaccharide encapsulated bacteria]] and organisms that invade erythrocytes.<ref>{{Cite journal|title = Detection, Education and Management of the Asplenic or Hyposplenic Patient - American Family Physician|url = http://www.aafp.org/afp/2001/0201/p499.html|journal = American Family Physician|access-date = 2016-02-16|first = Malcolm L.|last = Brigden|date = February 2001|volume = 63|issue = 3|page = 499}}</ref> People without a spleen have a weakened immune system, although other immune organs compensate for the missing spleen.<ref name="Splenectomy Results - Mayo Clinic">{{Cite web|url=http://www.mayoclinic.org/tests-procedures/splenectomy/basics/results/prc-20014837|title=Splenectomy Results - Mayo Clinic|website=www.mayoclinic.org|access-date=2016-03-03}}</ref>  [[Vaccination]] against encapsulated bacteria and prophylactic antibiotics can be used to counteract lowered immunity in asplenic patients. Specifically, people without a spleen are recommended to be vaccinated against [[pneumonia]], [[influenza]], ''[[Haemophilus influenzae]]'' type b and [[meningococci]].<ref name="Splenectomy Results - Mayo Clinic"/>

=== Testing for autosplenectomy ===
One of the spleen's main tasks is to filter the blood and remove and recycle damaged or old red blood cells.<ref>{{Cite web|url=http://www.chp.edu/our-services/transplant/liver/education/organs/spleen-information|title=What Is the Spleen? Functions & Info {{!}} Children's Hospital Pittsburgh|website=www.chp.edu|access-date=2016-03-03}}</ref> Splenic function can be measured by filtering capabilities, as indicated by number of Howell-Jolly bodies or pitted erythrocytes in the blood.<ref name="Brousse 165–176"/> Both of these tests examine whether or not the spleen is functioning normally by testing splenic outputs.

==== Howell-Jolly bodies ====
[[Howell–Jolly body|Howell–Jolly bodies]] are found on [[red blood cell]]s and contain chromatin remnants from basophilic cells.<ref>{{Cite journal|pmc = 4103047|title = Functional hyposplenism|last = Kirkineska|first = L|date = 2014|journal = Hippokratia|pmid = 25125944|volume=18|issue = 1|pages=7–11}}</ref> Under normal conditions, these nuclear remnants are removed from the blood by the spleen's filtering capabilities. Howell-Jolly bodies can be identified and quantified using a blood smear or by flow cytometry.<ref name="Brousse 165–176"/> A high number of Howell-Jolly bodies is indicative of splenic hypofunction and potentially autosplenectomy.

==== Pitted erythrocytes ====
Erythrocytes with membrane pits can be indicative of splenic dysfunction as a healthy spleen clears blood of pitted erythrocytes. Pitted erythrocytes can be counted using Normarsky optics.<ref>{{Cite journal|title = Post-splenectomy and hyposplenic states|last = Di Sabatino|first = Antonio|date = April 6, 2011|journal = Lancet|volume = 378|issue = 9785|pages = 86–97|doi = 10.1016/s0140-6736(10)61493-6 |pmid = 21474172|s2cid = 30554953}}</ref> Humans with healthy spleens have less than two percent of their red blood cells contain pits. In comparison, a person with asplenia may have up to 50% of their red blood cells contain pits.<ref>{{Cite web|url=http://www.rbclab.com/Pages/200/210/120%20Pit/210%20120.html|title=Red Blood Cell Pit Count|date=2010|website=Red Blood Cell Lab|publisher=Children's Hospital Oakland Research Institute|access-date=March 2, 2016}}</ref>

==Diseases that cause autosplenectomy==

===Sickle cell anemia===
The most frequent cause of autosplenectomy is [[sickle cell anemia]]<ref name=radio>{{cite web |url=http://radiopaedia.org/articles/autosplenectomy |title=Autosplenectomy |publisher=radiopaedia.org |access-date=30 December 2015 |author1=Henry Knipe |author2=Frank Gaillard }}</ref> which causes progressive splenic hypofunction over time. Increased deoxygenation causes sickling of red blood cells, which adhere to the spleen wall and splenic macrophages causing [[ischemia]].<ref name="Brousse 165–176"/>  This ischemia can result in splenic sequestration, where large amounts of blood pool in the spleen but do not flow within vasculature.<ref>{{Cite journal|url = http://aje.oxfordjournals.org/content/151/9/839.full.pdf|archive-url = https://web.archive.org/web/20150906103431/http://aje.oxfordjournals.org/content/151/9/839.full.pdf|url-status = dead|archive-date = 2015-09-06|title = Sickle Hemoglobin (Hb S) Allele and Sickle Cell Disease: A HuGE Review|last = Ashley-Koch|first = A|date = 2000|journal = American Journal of Epidemiology|volume = 151|issue = 9|pages = 839–845|doi = 10.1093/oxfordjournals.aje.a010288|pmid = 10791557}}</ref>

=== Pneumococcal sepsis ===
Pneumococcal sepsis, or whole-body infection caused by the ''Streptococcus pneumoniae'' bacteria, has been reported to cause autosplenectomy but is a very rare and poorly understood complication of the infection.<ref>{{Cite journal|title = Autosplenectomy and Antiphospholipid Antibodies in Systemic Lupus Erythematosus: A Pathogenic Relationship?|last = Santilli|first = Daniele|date = 2003|journal = Seminars in Arthritis and Rheumatism|volume = 33|issue = 2|pages = 125–133|doi = 10.1016/S0049-0172(03)00004-0|pmid = 14625820}}</ref>

==References==
{{reflist}}

[[Category:Immune system disorders]]
[[Category:Diseases of spleen]]