The Frequency of Complement Dysregulation in Hemolytic Uremic Syndrome Suspicious Cases- Two Centers Study

Background and Aim: Hemolytic uremic syndrome (HUS) consists of heterogeneous group of diseases which share same clinical and pathological manifestation. Complement consumption and dysregulation is one of the features in all subtypes of HUS. Classic and some inhibitory factors in the alternative pathway are usually measured in order to discriminate the subtype of HUS. We do not know how much these measurements were useful in our setting. The aim of this study is to find the percentage of abnormal level of complement in the assessment of underlying disease of HUS.Materials and Methods: This was a descriptive retrospective conducted between 2005 and 2017. Data of all children aged less than 18 years old suspicious to HUS and admitted in Ali-asghar children hospital or Mofid hospital were reviewed. Complement levels (C3,C4,CH50), inhibitory factors (H, I, B), CD46 , ADAMTS 13 , ADAMTS 13 AB were recorded and the laboratory cut point used to classify the complements to low , normal or high level.Results: 76 patients (36 females, 40 males) with mean age of 5.2 yrs (3 m -24 yrs) were analyzed. Diarrhea positive HUS in 6 (7.8%) ,pneumococcal HUS in1 (1.3%),TTP in 7(9.1)and 37patient with atypical HUS were diagnosed. The Most common clinical manifestation at the admission time was non bloody diarrhea (12.7%).The frequency of complement deregulation was shown in table 1. It should be considered that some of the patients had received FFP prior to check serum complement level. Patients with both factor H and I deficient consist 2.5% and 2.5% had low levels of all factors H, I, B.During the last 12 years, 25% of cases achieved full recovery, 5.2% died, and the rest are on renal replacement therapy.Conclusion: This study revealed that the routine panel of HUS is diagnostic in about 10% and expanding the diagnostic tests in addition genetic study for underlying disease is mandatory.