hemolytic uremic syndrome
ABBR: HUS
A severe, acute illness consisting of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney failure.
Incidence: About two cases each year are identified per 100,000 people in the U.S. Children are most often affected.
Causes: Escherichia coli 0157:H7, E. coli 0111, and E. coli 104 are causative agents that release a Shiga toxin that produces hemorrhagic colitis and HUS. They may be acquired from eating contaminated or inadequately cooked hamburger or other meats.
Symptoms and Signs: Patients often present with symptoms of gastroenteritis (nausea, vomiting, and diarrhea); some may have symptoms of upper respiratory infection. Hallmarks of the acute phase are a purpuric rash as a result of low platelets, along with irritability and lethargy. Urinary output is usually reduced and accompanied by renal failure. Other findings include splenomegaly, mild jaundice, seizures (in some patients), hepatomegaly, and /or pulmonary edema. The acute phase may last from 1 to 2 weeks in mild cases and much longer in severe cases.
Diagnosis: HUS is diagnosed when a child presents with the combination of three symptoms: acute kidney failure, thrombocytopenia, and hemolytic anemia with fragmentation of red blood cells seen on the peripheral blood smear.
Prevention: Appropriate food preparation techniques (avoiding contact with raw meat or its juices and cooking foods thoroughly to recommended temperatures) can prevent HUS and other food-borne illnesses.
Treatment: The treatment of this syndrome is management of the renal failure and anemia. Antibiotics are ineffective.
Impact on Health: The usual outcome is complete recovery, but about 5% of patients die; 10% develop end-stage renal disease and require lifelong hemodialysis.
Patient Care: If the child has been anuric for 24 hr or demonstrates oliguria with seizures and hypertension, the physician places a peritoneal catheter, and the nurse institutes peritoneal dialysis as prescribed, with fluid replacement based on estimated sensible and insensible losses. Fluid and electrolyte balance, complete blood count, body weight, sensorium, and vital signs are carefully monitored, and blood urea nitrogen and azotemia levels are followed to evaluate therapy. Hypertension is reported and controlled with antihypertensive drugs. Severe anemia is treated with fresh, washed, packed red blood cells; careful assessment is required throughout the transfusion to prevent circulatory overload, hypertension, and hyperkalemia. Seizures are managed by treating specific causes when known (hypertension, hyponatremia, hypocalcemia), and with anticonvulsant drugs as required. The patient is protected from injury during the seizure, with the airway guarded. Heart and breath sounds are auscultated periodically because cardiac failure with pulmonary edema can occur in association with hypervolemia. Prevention and treatment include water and sodium restriction and diuretic therapy if prescribed. Meeting the child's nutritional needs can be difficult because concentrated foods must be ingested without fluids and the child may be or become nauseated. The dietitian should be consulted for nutrition management. The very ill child may also be irritable, restless, anxious, and frightened by frequent painful and stressful tests and treatments. Comfort and stability are provided in this threatening environment. Whenever possible, arrangements are made for one or both parents to remain with their child at all times. Support and reassurance are given to the parents and significant others, who are also stressed by the severity of the illness and who may experience a degree of guilt if the illness resulted from ingestion of contaminated or raw foods. The family benefits not only from explanations about tests and treatments and information about their child's progress but also from sympathetic listening.
SYN: Shiga toxin-mediated thrombotic microangiopathy.