Objective: To determine if interventions during the pre-hemolytic uremic syndrome (HUS) diarrhea phase are associated with maintenance of urine output during HUS.

Methods: Prospective observational cohort study. Methods: Eleven pediatric hospitals in the United States and Scotland. Methods: Children younger than 18 years with diarrhea-associated HUS (hematocrit level <30% with smear evidence of intravascular erythrocyte destruction), thrombocytopenia (platelet count <150 × 10³/mm³), and impaired renal function (serum creatinine concentration > upper limit of reference range for age). Methods: Intravenous fluid was given within the first 4 days of the onset of diarrhea. Methods: Presence or absence of oligoanuria (urine output ≤ 0.5 mL/kg/h for >1 day).

Results: The overall oligoanuric rate of the 50 participants was 68%, but was 84% among those who received no intravenous fluids in the first 4 days of illness. The relative risk of oligoanuria when fluids were not given in this interval was 1.6 (95% confidence interval, 1.1-2.4; P = .02). Children with oligoanuric HUS were given less total intravenous fluid (r = -0.32; P = .02) and sodium (r = -0.27; P = .05) in the first 4 days of illness than those without oligoanuria. In multivariable analysis, the most significant covariate was volume infused, but volume and sodium strongly covaried.

Conclusions: Intravenous volume expansion is an underused intervention that could decrease the frequency of oligoanuric renal failure in patients at risk of HUS.