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23 Cards in this Set
- Front
- Back
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What is hemolytic uremic syndrome (HUS)?
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Characterized by microangiopathic anemia, thrombocytopenia, and acute renal failure.
In children most common is acute renal failure. Syndrome may follow an episode of diarrhea, the use of drugs (CSA), malignancy or glomerulopathies or it may be idiopathic. |
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What is the incidence of HUS?
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1 in 100, 000 people.
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What pathogens can cause HUS?
a. E. Coli b. Salmonella c. Campylobacter d. none of the above e. all of the above f. a and b |
e. all of the above
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HUS can be associated with diarrhea (D+) or without diarrhea (D-). T/F
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True
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HUS with diarrhea is more common in the summer months and in early fall and usually occurs in children age 7 months to 6 years. T/F
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True
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HUS D- may follow a respiratory illness but does not follow a prodromal illness. D- is not season associated, is seen in adults and occurs sporadically. T/F
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True
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HUS does not have genetic forms. T/F
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False- HUS does have familial forms and are usually preceded by a diarrheal illness. It is often recurrent and associated with a guarded long-term prognosis regarding maintenance of normal kidney function.
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HUS D+ is usually preceded by a colitis caused by Shiga-toxin producing E. Coli. T/F
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True
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What is the pathophysiology of HUS?
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Inflammation of the colon leads to systemic absorption of the Shiga toxin and lipopolysaccharide from the GI tract. These toxins bind to globotriaosylceramide, a glyco-lipid receptor molecule on the surface of the endothelial cells in the gut and kidney. The damaged endothelial cells of the glomerular capillaries release vasoactive and platelet-aggregating substances. the endothelial cells swell and fibrin is deposited on the injured vessel walls. This swelling and microthrombi formation within the glomerular capillaries produce a localized intravascular coagulopathy. The golmerular filtration rate is reduced and renal insufficiency ensues. Erythrocytes are damaged and fragmented as they flow through the glomerular capillaries. This leads to microangiopathic hemolytic anemia. Hemolysis can be due to lipid peroxidation.
Resulting thrombocytopenia is thought to be the result of platelet destruction, increased consumption, liver and spleen sequestration and intrarenal aggregation. |
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What is the clinical presentation of HUS?
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Symptoms can vary based from subclinical to life threatening.
HUS D+ - several days of diarrhea w/ or w/o vomiting, followed by weakness, lethargy, irritability and pallor. - bloody diarrhea in 80-90%. - restlessness - oliguria - edema - macroscopic hematuria * Clinical picture may resemble that of someone with symptoms of acute abdomen Heme Symptoms - hemolysis - thrombocytopenia - thrombi in organs - thrombotic ischemia in gut or colon, in CNS Renal Symptoms - acute renal insufficiency with onset of hemolysis - frequent watery stools may mask decreased urine output - oliguria develops 1 day to 2 weeks after the onset of diarrhea in D+ HUS. CNS Symptoms - D- HUS associated with a greater number of neurologic symptoms than D+ HUS - sudden onset of lethargy and irritability - ataxia, coma, seizures, cerebral swelling, hemiparesis (changes may be caused ischemia from microthrombi or by the effects of HTN, hyponatremia and uremia) GI symptoms - D+ HUS is preceded by diarrhea - intestinal necrosis - mild pancreatic involvement is common - jaundice may be present Infection - fever - leukocytosis - rectal prolapse, some may need surgery for gangrene Cardiovascular Symptoms - CHF (HTN, pallor, lethargy, irritability, abdominal pain, peripheral edema) |
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What is hemolytic uremic syndrome (HUS)?
|
Characterized by microangiopathic anemia, thrombocytopenia, and acute renal failure.
In children most common is acute renal failure. Syndrome may follow an episode of diarrhea, the use of drugs (CSA), malignancy or glomerulopathies or it may be idiopathic. |
|
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What is the incidence of HUS?
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1 in 100, 000 people.
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What pathogens can cause HUS?
a. E. Coli b. Salmonella c. Campylobacter d. none of the above e. all of the above f. a and b |
e. all of the above
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HUS can be associated with diarrhea (D+) or without diarrhea (D-). T/F
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True
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HUS with diarrhea is more common in the summer months and in early fall and usually occurs in children age 7 months to 6 years. T/F
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True
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HUS D- may follow a respiratory illness but does not follow a prodromal illness. D- is not season associated, is seen in adults and occurs sporadically. T/F
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True
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HUS does not have genetic forms. T/F
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False- HUS does have familial forms and are usually preceded by a diarrheal illness. It is often recurrent and associated with a guarded long-term prognosis regarding maintenance of normal kidney function.
|
|
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HUS D+ is usually preceded by a colitis caused by Shiga-toxin producing E. Coli. T/F
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True
|
|
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What is the pathophysiology of HUS?
|
Inflammation of the colon leads to systemic absorption of the Shiga toxin and lipopolysaccharide from the GI tract. These toxins bind to globotriaosylceramide, a glyco-lipid receptor molecule on the surface of the endothelial cells in the gut and kidney. The damaged endothelial cells of the glomerular capillaries release vasoactive and platelet-aggregating substances. the endothelial cells swell and fibrin is deposited on the injured vessel walls. This swelling and microthrombi formation within the glomerular capillaries produce a localized intravascular coagulopathy. The golmerular filtration rate is reduced and renal insufficiency ensues. Erythrocytes are damaged and fragmented as they flow through the glomerular capillaries. This leads to microangiopathic hemolytic anemia. Hemolysis can be due to lipid peroxidation.
Resulting thrombocytopenia is thought to be the result of platelet destruction, increased consumption, liver and spleen sequestration and intrarenal aggregation. |
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What is the clinical presentation of HUS?
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Symptoms can vary based from subclinical to life threatening.
HUS D+ - several days of diarrhea w/ or w/o vomiting, followed by weakness, lethargy, irritability and pallor. - bloody diarrhea in 80-90%. - restlessness - oliguria - edema - macroscopic hematuria * Clinical picture may resemble that of someone with symptoms of acute abdomen Heme Symptoms - hemolysis - thrombocytopenia - thrombi in organs - thrombotic ischemia in gut or colon, in CNS Renal Symptoms - acute renal insufficiency with onset of hemolysis |
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How is the diagnosis of HUS made?
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By history and symptoms
- Microangiopathic hemolytic anemia, trhombocytopenia, and acute renal failure following an episode of bloody diarrhea Labs - cbc - coombs - chem 10 - coag panel - UA - elevated WBC - elastase is a catabolic enzyme - Von Willebrand factor frequently abnormal in amount |
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What is the treatment for HUS?
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- Supportive care
- Dialysis if indicated - IVIG may hasten recovery in patients with thrombocytopenia and oliguria - antihypertensives and diuretics to control HTN and fluid overload |
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What is the prognosis for HUS?
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D+ HUS have a better outcome than patients with D- HUS. HUS has been associated with severe pneumococcal infections and carries a poorer prognosis that those caused by E Coli.
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