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Unlabelled: Atypical hemolytic uremic syndrome (HUS) refers to the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury in the absence of Shiga toxin-producing Escherichia coli exposure or Streptococcus pneumoniae infection. Currently, approximately 50 % of the atypical cases have demonstrable mutations in complement regulatory proteins. Historically, the diagnosis of atypical HUS portends a poor prognosis with a high rate of disease recurrence, progression to end-stage renal disease, and death. However, it is now evident that atypical HUS actually encompasses a heterogeneous group of disorders, and there are reports suggesting that some cases of atypical HUS have a favorable prognosis, similar to that of diarrhea-associated disease. We present three patients with the atypical HUS phenotype who had complete renal recovery and no disease recurrence. We believe it is important to distinguish those cases of atypical HUS associated with disorders of complement regulatory proteins from other idiopathic causes of nondiarrheal HUS given the implications for prognosis and treatment.Conclusion: Given the heterogeneous nature and variable prognosis of atypical HUS, treatment should be carefully considered prior to the use of long-term plasma therapy and/or eculizumab. [ABSTRACT FROM AUTHOR]

Streptococcus pneumoniae-associated hemolytic uremic syndrome (HUS) is an underrecognized condition that mainly occurs in young children. Early diagnosis is important because of the potential to improve morbidity and mortality rates. The purposes of this report are to review the clinical and laboratory features of 14 patients with pneumococcal HUS and present a modified classification to capture cases that may not have been documented with a diagnosis of pneumococcal HUS. We thereby provide a rationale for including patients with concurrent disseminated intravascular coagulopathy and/or those whose culture results were negative, and we highlight the emergence of serotype 19A subsequent to the introduction of 7-valent pneumococcal protein conjugate vaccine (Prevnar). This is the largest series of such subjects (to our knowledge) from a single center. Sixty-four percent of the patients recovered without any long-term sequelae. Three patients developed chronic kidney disease, 1 developed end-stage renal failure, and 1 died in the acute phase. The greatest risk factor for the development of chronic kidney disease is the need for acute dialysis for >20 days, and death in the acute phase is rare unless meningitis is the primary infection. [ABSTRACT FROM AUTHOR]