Hemolytic-uremic syndrome

Infobox_Disease
Name = PAGENAME


Caption =
DiseasesDB = 13052
ICD10 = ICD10|D|59|3|d|55
ICD9 = ICD9|283.11
ICDO =
OMIM = 235400
MedlinePlus =
eMedicineSubj = ped
eMedicineTopic = 960
MeshID = D006463
In medicine, hemolytic-uremic syndrome (or haemolytic-uraemic syndrome, abbreviated HUS) is a disease characterized by microangiopathic hemolytic anemia, acute renal failure and a low platelet count (thrombocytopenia).

igns and symptoms

The classic childhood case of HUS occurs after bloody diarrhea caused by , a strain of "E. coli" that expresses verotoxin (also called Shiga toxin). The toxin enters the bloodstream, attaches to renal endothelium and initiates an inflammatory reaction leading to acute renal failure (ARF) and disseminated intravascular coagulation (DIC). The fibrin mesh destroys red blood cells and captures thrombocytes, leading to a decrease of both on complete blood count. The usual age of onset is between 2 and adolescence.

HUS occurs after 2-7% of all "E. coli" O157:H7 infections.

Adult HUS has similar symptoms and pathology but is an uncommon outcome of the following: HIV; antiphospholipid syndrome (associated with Lupus erythematosus and generalized hypercoagulability); post partum renal failure; malignant hypertension; scleroderma; and cancer chemotherapy (mitomycin, cyclosporine, cisplatin and bleomycin).

A third category is referred to as familial HUS. It represents 5-10% of HUS cases and is largely due to mutations in the complement proteins factor H, membrane cofactor protein and factor I leading to uncontrolled complement system activation. Recurrent thromboses result in a high mortality rate.

Diagnosis

Clinically, HUS can be very hard to distinguish from thrombotic thrombocytopenic purpura (TTP). The laboratory features are almost identical, and not every case of HUS is preceded by diarrhea. HUS is characterized by the triad of hemolytic anemia, thrombocytopenia, and acute renal failure. The only distinguishing feature is that in TTP, fever and neurological symptoms are often present; but this is not always the case.

Treatment

Antibiotic treatment of O157:H7 colitis may stimulate further verotoxin production and thereby increase the risk of HUS. [ [http://www.emedicine.com/EMERG/topic238.htm eMedicine - Hemolytic Uremic Syndrome : Article by William Shapiro ] ]

Treatment is generally supportive with dialysis as needed. However untreated HUS in adults may progress to end organ damage. Platelet transfusion may actually worsen outcome.

In severe cases or when there is diagnostic uncertainty between HUS and TTP, plasmapheresis is the treatment of choice. Plasmapheresis may reverse the ongoing platelet consumption. In children with post diarrheal HUS, there is greater chances of spontaneous resolution and hence observation may be the key modality.

Prognosis

With aggressive treatment > 90% survive acute phase. About 9% may develop end stage renal disease.About one-third of persons with "hemolytic-uremic syndrome" have abnormal kidney function many years later, and a few require long-term dialysis. Another 8% of persons with hemolytic uremic syndrome have other lifelong complications, such as high blood pressure, seizures, blindness, paralysis, and the effects of having part of their colon removed. The overall mortality rate from HUS is 5-15%. Older children and adults have a worse prognosis. [cite book | author = Chu P, Hemphill RR | year = 2004 | title = Emergency Medicine: A Comprehensive Study Guide | chapter = 222: Acuired hemolytic anemia | editor = Tintinalli JE, Kelen GD, Stapczynski JS | edition = 6th Edition | publisher = McGraw-Hill | location = New York, NY ISBN 0-07-138875-3]

Epidemiology

HUS has a peak incidence between 6 months and 4 years of age. [cite journal | author=Corrigan JJ Jr, Boineau FG | title=Hemolytic-uremic syndrome | journal=Pediatr Rev | year=2001 | pages=365–9 | volume=22 | issue=11 | pmid= 11691946 ]

HUS and the "E. coli" infections which caused it have been the source of much negative publicity for the Food and Drug Administration (FDA), meat industries, and fast-food restaurants since the 1990's, especially in the Jack in the Box contaminations. It was also featured in the Robin Cook novel "Toxin". In 2006, an epidemic of harmful "E. coli" emerged in the United States due to contaminated spinach. 183 known cases have been reported, including 29 cases of HUS.

ee also

*
* Shigellosis
* Microangiopathic hemolytic anemia

References

External links

* [http://www.about-hus.com/ "About HUS" website]