Hemolytic Uremic Syndrome: A Contemporary Pediatric Experience

Background: Hemolytic uremic syndrome (HUS) is a significant cause for complicated acute kidney injury. In Western countries, >90% of HUS are Shiga toxin Escherichia coli (STEC) associated. Methods: This is a retrospective review of all Israeli children diagnosed with HUS in 4 major medical centers in Israel during 1999-2016. Patients were categorized into 4 HUS etiological groups according to international guidelines: I, inherited or acquired damage to the complement cascade ("atypical HUS" [aHUS]); II, infection associated ("typical" HUS-STEC associated, Pneumococcus); III, coexisting disease; IV: other and unknown causes. Results: Seventy-five children with HUS were identified; the mean annual incidence was 1.5 ± 0.7 cases/10⁶ per year. Distribution according to etiological groups was: I: 24.0%; II: 14.7%; III: 9.3%; IV: 52.0%. Group I comprised high proportions of Arabs (55.6%), children of consanguineous parents (61.0%), and hypertension. Group II included a high proportion of children with diarrhea on presentation and central nervous system involvement. Only 5 (6.6%) had proven STEC-HUS. Group IV was similar in most characteristics to group II. Logistic regression analysis revealed 3 independent factors associated with the diagnosis of aHUS: consanguinity, lack of diarrhea, and lack of leukocytosis at presentation. Receiver operating analysis curve showed an area under the curve of 0.9 (95% CI 0.82-0.98). Conclusions: HUS incidence is lower in Israel than in most countries, especially because STEC-HUS is very rare. aHUS is the largest defined etiological group; some distinctive characteristics were identified that could facilitate its diagnosis. The current classification system leaves a high rate of "unknown cause" HUS.