1
Fifth stage
Pediatric
Lec-5
د.ندى العلي
19/10/2015
Hemolytic-Uremic Syndrome
Hemolytic-uremic syndrome (HUS) is defined as the triad of acute microangiopathic
hemolytic anemia, thrombocytopenia, and acute renal insufficiency or failure
It occur as a common pathway resulting from a variety of initiating causes:
epidemic, diarrhea-associated HUS is the most common form.
Atypical HUS (also known as sporadic or nondiarrhea-associated HUS) occurs less
frequently in children and is classified according to the suspected underlying primary
cause
Typically the illness affects infants and young children of all races and both genders,
with the majority of diarrhea-associated cases occurring in the summer months.
Even in nonepidemic areas, cases commonly cluster. Although the frequency varies,
typical childhood HUS is one of the most common causes of acute renal failure among
pediatric patients.
The diarrheal form of HUS in children is associated most commonly with colonic
infection by
Escherichia coli
( most commonly E. coli subtype 0157:H7)
capable of producing a Shiga-like toxin
HISTORY
The child who has typical HUS usually experiences a 3- to 10-day prodrome of bloody
or watery diarrhea often associated with cramping abdominal pain.
Nausea, vomiting, and fever are present variably
Extreme pallor and malaise, when reported, usually occur suddenly at a time when the
gastrointestinal illness has appeared to have stabilized or improved .
Acute gastrointestinal manifestations may include
abdominal distention, bleeding, intussusception, rectal prolapse, and strictures.
Gangrene of the colon and intestinal perforation also have been reported.
Extrarenal involvement in HUS often is seen
CNS abnormalities such as somnolence, irritability, seizures, or stroke ,
In atypical HUS a prodrome usually is absent or consists of an upper respiratory tract
infection.
The manifestations at the onset of HUS are similar, except that gastrointestinal
complaints are less common .
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PHYSICAL FINDINGS
Children who have HUS usually appear acutely ill with pallor, petechiae, and/or
purpura.
They often are irritable or drowsy and may have hypertension.
Hepatomegaly frequently is present.
The presence of congestive heart failure and pulmonary or peripheral edema results
from a combination of oliguria with consequent intravascular volume overload and/or
a rapidly developing anemia
LABORATORY FINDINGS
A Coombs-negative and anemia is a typical finding.
The blood smear shows the fragmented erythrocytes characteristic of the
microangiopathic process as well as the thrombocytopenia.
Leukocytosis often is present, and is frequently associated with more severe disease.
The urinalysis usually demonstrates proteinuria, microscopic or macroscopic hematuria
Laboratory abnormalities resulting from renal dysfunction,
including azotemia, hyperkalemia, hyperphosphatemia, and metabolic acidosis, are
variable in their degree depending on the magnitude and duration of the renal disease
and the degree of red cell hemolysis .
the child who has suspected HUS should have some form of electrocardiographic
monitoring until the initial laboratory data are obtained .
Atypical HUS is more common in older children and adults, although diarrhea-
associated HUS is being recognized with increasing frequency. The occurrence of
atypical HUS tends to be sporadic without geographical or seasonal characteristics
DIFFERENTIAL DIAGNOSIS
The features of HUS are not specific and also may occur in disseminated intravascular
coagulation (DIC), overwhelming sepsis, malignant hypertension, and some instances of
vasculitis
TREATMENT
Management of the oliguric acute renal failure, hypertension, anemia, and CNS
disturbances is the most common initial therapeutic consideration in patients who
have HUS.
Prevention of fluid overload (which often provokes significant worsening of
hypertension), correction of electrolyte imbalances, and control of uremia is achieved
by careful medical management and, if necessary, dialysis .
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To avoid rapid changes of intravascular volume, where possible, blood cells should be
transfused in small quantities as needed
Seizures should be treated aggressively and conventionally
PROGNOSIS
More than 80% of children who have typical childhood HUS recover without renal or
CNS sequelae.
More than 10% may have some degree of persistent renal insufficiency or
hypertension
Children who have atypical HUS are at increased risk for permanently impaired renal
function.
Patients who have recurrent or familial forms of HUS also are at increased risk for
progressive deterioration of renal function