HUS Flashcards
Triad of HUS
1) Microangiopathic hemolytic anemia 2) Thrombocytopenia 3) Renal insufficiency
MC HUS is caused by
Toxin-producing E. coli producing diarrhea-associated HUS
MC E. coli serotype that causes HUS in Europe and the Americas
O157:H7
Toxin of this organism is causative of HUS in Asia and southern Africa
Shigella dysenteriae type I
Toxin of this organism is causative of HUS in Western countries
STEC
Reservoir of STEC
Intestinal tract of domestic animals, usually cows
HUS is commonly transmitted by
Undercooked meat or unpasteurized (raw) milk and apple cider
HUS develops during acute infection with this organism, typically manifesting with pneumonia and empyema
Neuraminidase-producing S. pneumoniae
Pathology of HUS nephritis
Capillary and endothelial injury leading to localized thrombosis, particularly in the glomeruli, causing a direct decrease in GFR; consumptive thrombocytopenia; microangiopathic hemolytic anemia from mechanical damage to RBCs as they pass through damaged thrombotic vasculature
HUS is MC in what age group
Preschool and school-aged children
Timing of nephritis in HUS caused by E. coli
Few days after onset of AGE
Diarrhea in HUS is characteristically bloody
F, not necessarily
T/F No presenting features reliably predict the severity of HUS in any given patient
T
Significant life-threatening electrolyte abnormality in HUS nephritis
Hyperkalemia (from ARF and hemolysis)
HUS: CNS involvement occurs in ___% of cases
20
T/F Majority of patients with HUS have some CNS involvement
T
Severe CNS involvement in HUS results from
Focal ischemia sec to microvascular CNS thrombosis
T/F In HUS, large strokes and ICH are common
F, rare
Cell type that can be seen on PBS of patients with HUS
Schistocytes from hemolysis
T/F PT/PTT in HUS is usually derranged
F, usually normal
T/F Coombs’ test in HUS is usually positive
F, usually (-) and T if HUS is pneumococci-induced
T/F The presence or absence of toxigenic organisms on stool culture has little role in making the diagnosis of diarrhea-associated, enteropathic HUS
T
T/F Stool culture is often negative in patients who have diarrhea-associated HUS
T
HUS may take place without diarrheal nor pneumococcal prodrome
T, as in genetic HUS
Patients with this type of HUS are more prone to recurrence and has a more severe prognosis
Genetic
T/F Most patients with HUS nephritis recover renal function completely
T
T/F Prognosis for HUS not associated with diarrhea is more severe
T
T/F Early intravenous volume expansion before the onset of oligo anuria may be nephroprotective in diarrhea-associated HUS
T
T/F Red cell transfusions are not required in HUS since hemolysis is part of it’s pathophysiology
F, usually required as hemolysis can be brisk and recurrent until the active phase of the disease has resolved
Why is it critical that any administered red cells to HUS patients be washed before transfusion?
To remove residual plasma since endogenous IgM directed against revealed T antigen can play a role in accelerating the pathogenesis of the disease.
T/F In HUS, platelets should generally not be administered
T, because they are rapidly consumed by the active coagulation and theoretically can worsen the clinical course
T/F Despite low platelet counts, serious bleeding is very rare in patients with HUS
T
Antibiotic therapy to clear enteric toxigenic organisms (STEC) is not recommended in HUS because
It can result in increased toxin release, potentially exacerbating the disease, specifically in O157-H7-associated HUS
T/F Antibiotic therapy against pneumococci -associated HUS is not indicated
F, prompt therapy is important
Plasma infusion or plasmapheresis is contraindicated in which type of HUS
Pneumococcal-associated HUS as it could exacerbate the disease
Treatment for HUS which is an anti-C5 antibody that inhibits complement activation, a pathway that contributes to active disease in some forms of atypical familial HUS
Eculizumab
T/F Most patients with diarrhea-associated HUS recover completely with little risk of long-term sequelae
T
