title: Atypical Hemolytic Uremic Syndrome and Chronic Ulcerative Colitis Treated with Eculizumab.
abstract: BACKGROUND
  Hemolytic-uremic syndrome (HUS) presents with hemolytic anemia, thrombocytopenia, and thrombotic microangiopathy of the kidney and usually results from Shiga-toxin induced activation of the alternative complement pathway. Gastroenteritis is a common feature of the Shiga-toxin producingEscherichia coliHUS, referred to as STEC-HUS. An inherited or acquired complement dysregulation may lead to HUS referred to as non-STEC or atypical (a)HUS. Although gastroenteritis is not a common presentation of aHUS, some patients develop ischemic colitis and may be misdiagnosed as acute appendicitis or acute ulcerative colitis (UC).
  We present a patient with low circulating complement (C) 3 levels who developed aHUS in the course of chronic active UC. Resolution of renal and gastrointestinal manifestations in response to treatment with eculizumab, a humanized monoclonal antibody against terminal C5 protein suggests the role of alternative complement in the pathogenesis of both, aHUS and UC.
  
  
  CONCLUSIONS
  This case illustrates that dysregulation of the alternative complement pathway may manifest in other organs besides the kidney and that the circulating C3 levels do not correlate with the disease activity or the clinical response to eculizumab.
authors.affiliation: Department of Pediatric Nephrology, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, USA.
authors.forename: Tennille N
authors.initials: TN
authors.lastname: Webb
authors.affiliation: Department of Pediatrics, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, USA.
authors.forename: Heidi
authors.initials: H
authors.lastname: Griffiths
authors.affiliation: Department of Pediatric Nephrology, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, USA.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Miyashita
authors.affiliation: Department of Gastroenterology, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Riha
authors.initials: R
authors.lastname: Bhatt
authors.affiliation: Department of Pathology, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Ronald
authors.initials: R
authors.lastname: Jaffe
authors.affiliation: Department of Pediatric Nephrology, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Moritz
authors.affiliation: Department of Pediatrics, Innsbruck Medical University, Austria.
authors.forename: Johannes
authors.initials: J
authors.lastname: Hofer
authors.affiliation: Department of Pediatric Nephrology, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, USA.; Department of Clinical Biology and Physiology, University of Pittsburgh School of Medicine, One Children's Hospital Drive, 4401 Penn Avenue, Pittsburgh, Pennsylvania, USA.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Swiatecka-Urban
keywords: Hemolytic–uremic syndrome (HUS); acute kidney injury (AKI); inflammatory bowel disease (IBD); membrane attack complex (MAC); thrombotic microangiopathy (TMA); ulcerative colitis (UC)