Non-enteropathic hemolytic uremic syndrome: Causes and short-term course

Background: Nondiarrheal or Streptococcus pneumoniae-related hemolytic uremic syndrome (HUS) represents a heterogeneous group of disorders. This study was performed to: (1) describe the current incidence, causes, demographic features, hospital courses, and short-term outcomes of non-enteropathic HUS; (2) compare findings in patients with non-enteropathic HUS with those obtained from a contemporaneous cohort of children with enteropathic or diarrhea-associated HUS (D+ HUS) diagnosed and treated at the same clinical sites; and (3) identify clinical or laboratory features that differentiate these 2 groups and predict disease severity and the short-term outcome in patients with non-enteropathic HUS. Methods: Data were collected from patients screened between 1997 and 2001 for enrollment in a multicenter trial of SYNSORB Pk (SYNSORB Biotech Inc, Calgary, Alberta, Canada) in D+ HUS, but who were ineligible because of lack of a diarrhea prodrome. The following features were recorded: age; sex; ethnicity; prodromal symptoms; cause; nadir values for hemoglobin, hematocrit, and platelet count; use of dialysis; and length of hospitalization. Results: Twenty-seven of 247 children with HUS had non-enteropathic HUS (11%). Twenty-four patients (15 boys, 9 girls), whose medical records were complete and available for review, comprise the study cohort. Mean age at onset was 4.2+/-0.9 (SE) years. Infection caused by S pneumoniae was diagnosed in 9 patients (38%). Dialysis was performed in 17 patients (71%) for 40+/-27 days. Median length of hospitalization was 22 days (range, 2 to 71 days). Children with S pneumoniae-related HUS had a longer hospital stay than those with other causes of non-enteropathic HUS, but all patients with S pneumoniae-related HUS recovered kidney function. Dialysis therapy was required more often (17 of 24 versus 59 of 145 children; P=0.025) and hospital stays were longer (median, 22 versus 9 days; P=0.002) in children with non-enteropathic HUS compared with patients with D+ HUS who were enrolled in the SYNSORB Pk clinical trial. Conclusion: (1) The incidence of non-enteropathic HUS is approximately one tenth that of D+ HUS; (2) patients with non-enteropathic HUS require dialysis therapy more often and are hospitalized more than twice as long during the acute episode compared with those with D+ HUS; (3) infection caused by S pneumoniae accounts for nearly 40% of cases of non-enteropathic HUS; and (4) although S pneumoniae-related HUS is associated with a less favorable short-term course than other types of non-enteropathic HUS or D+ HUS, the long-term prognosis for recovery of renal function appears to be good in these patients.