Background: HUS is defined by simultaneous occurrence of microangiopathic hemolytic anemia, thrombocytopenia and acute kidney injury. HUS etiologies include: infection associated ("typical" HUS - STEC associated, Pneumococcus and others), inherited or acquired damage to the complement cascade ["atypical" (a-) HUS], underlying conditions or other yet undefined mechanisms. In Western countries > 90% of HUS are STEC associated.
Methods: Retrospective review of all Israeli children diagnosed with HUS in Israel`s 4 major medical centers between 1999-2016. Patients were allocated into one of 4 HUS etiological groups according to international guidelines: I: aHUS; II: infection associated; III: coexisting disease; IV: other/unknown cause.
Results: 76 HUS children were identified, 1 excluded )ADAMTS13 activity <5%). Characteristics: median age (IQR): 23 (0.3-186) months; males: 46%; Jewish origin: 67%; parental consanguinity: 23.6%; annual incidence: 1.5±0.7/106. After a median follow up period of 38 (15-95) months, 5.3% of children died of HUS, 5.3% remain on dialysis, 6.6 % have been transplanted and 17.3% have CKD >2. Groups allocation: I: 24%; II: 14.7%; III: 9.3%; IV: 52%. There were significantly more Arab origin, consanguinity, hypertension and less diarrhea in group I. Group II children had higher CNS involvement. Only 5.3% had proven STEC-HUS (although this may be an underestimation). Group IV was similar in most characteristics to group II.
Conclusions: HUS general incidence is lower in Israel, compared to most countries, especially because STEC-HUS is very rare. aHUS is the largest defined etiological group, but the current classification system leaves a high rate of "unknown cause" HUS.
