OBJECTIVETo investigate the clinical characteristics, renal pathology, treatment and prognosis of children with atypical hemolytic uremic syndrome associated with H factor antibody.

METHODFour children less than 18 yr of age admitted from Nov. 2010 to May 2011 in Peking University First Hospital were included. They all met the criteria for atypical hemolytic uremic syndrome and with positive serum anti factor H antibody. They aged from 5 to 11 yr. Data on clinical manifestations, renal pathology, treatment and prognosis were analyzed.

RESULTAll of the 4 cases had gastrointestinal symptoms such as vomiting, abdominal pain, or abdominal distension. None of them had diarrhea. Two children had hypertension. One child had episodes of convulsion. One child had history of atypical hemolytic uremic syndrome. All of them had low serum complement C3. Three of them had low serum factor H (38.0, 88.4, 209.4 mg/L). All of them had serum antibody to factor H (1: 7 068, 1: 1 110, 1: 174, and 1: 869). Three of them received renal biopsy, all of them showed thrombotic microangiopathy. All of them were treated with steroid combined with mycophenolate mofetil. Two children received plasma exchange. They were followed up for 8 to 29 months. The renal function became normal and proteinuria relieved in all of them. The serum factor H concentration increased to 405.8, 155.8 and 438.4 mg/L, respectively. The titer of anti factor H antibody decreased to 1: 119, 1: 170, 1: 123, and 1: 674, respectively.

CONCLUSIONGastrointestinal symptom is common in children with atypical hemolytic uremic syndrome associated with H factor antibody. Hypocomplementemia was observed in all of them. Steroid combined with mycophenolate mofetil seemed to be effective for them. The monitoring of serum factor H and antibody to factor H may help diagnosis and treatment.