The pathogenesis and treatment of hemolytic uremic syndrome
The pathogenesis and treatment of hemolytic uremic syndrome. Kaplan BS, Meyers KE, Schulman SL. Journal of the American Society of Nephrology 1998;9(6):1126-1133.
Shiga-toxin-associated hemolytic uremic syndrome (Stx HUS) is a more accurate term for HUS caused by Stx-producing Escherichia coli (STEC), rather than diarrhea-associated hemolytic uremic syndrome (D+HUS) because some patients with Stx-HUS do not have diarrhea. D+HUS is used in this review, however, when referring to studies that did not confirm the existence of STEC. Similarly, there are several etiologies for non-Stx HUS; the authors proposed that atypical HUS should be referred to as idiopathic HUS given that inherited types of HUS have been included under the rubric of atypical D-HUS in the past. This distinction is important given the epidemiologic, clinical, laboratory, and prognostic variations in the different forms of HUS. This paper reviews these two types of HUS but this summary focuses on Stx HUS. STEC are the major cause of hemorrhagic colitis and are responsible for most cases of HUS. In Stx HUS, manifestations of acute renal failure predominate over those of brain involvement. In addition, the pancreas, lungs, heart and other organs may be injured. More than 95% of patients with HUS caused by Stx-producing Escherichia coli recover from the acute illness and recurrences are unusual. Mildly affected patients have the triad of features (sudden onset of hemolytic anemia, thrombocytopenia, and acute renal injury), whereby HUS is defined, but they never develop anuria. They almost never have seizures, are rarely hypertensive, and do not require dialysis. Their outcomes are uniformly excellent. Severely affected patients are anuric for more than 24 hours, may have seizures, often develop hypertension, require dialysis for optimum management, and may progress to end-stage renal failure. There are no consistent correlations of outcome in relation to age of onset in childhood, although adults with D+HUS have poorer outcomes than children. The occurrence of hemorrhagic colitis is a favorable prognostic sign because this is a hallmark of D+HUS (even in adults), although patients with a prolonged diarrheal phase have a worse outcome than those with a short period of diarrhea. Prolonged anuria, intestinal gangrene, or rectal prolapse are also associated with a poorer outcome. Hypertension during the acute phase of D+HUS does not necessarily mean that antihypertensive treatment is required in the future. Minor neurologic dysfunction does not predict outcome. The initial neutrophil count is significantly higher in patients with poor outcomes, as is the plasma concentration of PAI-1 (a prothrombotic substance). End-stage renal failure occurs in a small number of patients after apparent recovery. The length of the period of anuria is an important predictor of chronic renal failure. Patients who were anuric in the acute phase should receive follow-up care for many years to monitor protein excretion, hypertension, and elevation of serum creatinine.