Hemoglobinuria for the early identification of STEC-HUS in high-risk children: data from the ItalKid-HUS Network.

Hemolytic uremic syndrome (HUS) represents one of the main causes of severe acute kidney injury in children. The most frequent form of HUS is caused by Shiga toxin-2 (Stx2)-producing Escherichia coli. Hemoglobinuria and hematuria are markers of glomerular damage, but their use has never been validated in HUS. We retrospectively analyzed the presence of hemoglobinuria/urinary red blood cells (RBCs) in children with Stx2-positive bloody diarrhea (BD) or with already ongoing STEC-HUS with the aim of validating its role in early identifying HUS. We reviewed all the pediatric patients with Stx2+ BD (group 1) and with ongoing HUS (group 2) referred to our center from 2010 to 2019. A total of 100 children were eligible for the study. In group 1, 22 patients showed hemoglobinuria/hematuria, while 41 remained negative. In 15/22 positive patients (68.2%), blood tests ruled in HUS, while in 7 (31.8%), HUS was excluded. Among the 41 patients persistently negative for hemoglobinuria/hematuria, no one developed HUS. The 37 STEC-HUS children (group 2) all had hemoglobinuria/RBCs at admission.Conclusion: Hemoglobinuria/hematuria for the diagnosis of HUS in children with Stx2+ BD showed a sensitivity of 100% and a specificity of 85%. We strongly recommend patients with BD carrying Stx2 in stools to be closely monitored with urine dipstick/urinalysis to early identify HUS. What is Known • Children with bloody diarrhea secondary to Shiga toxin 2 are at high risk of hemolytic uremic syndrome, thus have to be carefully monitored for the development of the disease, in order to early be hospitalized and treated. What is New • Urine dipstick for hemoglobinuria can be used as an easy, inexpensive, and repeatable tool to early diagnose children with bloody diarrhea secondary to Shiga toxin 2 to have developed hemolytic uremic syndrome, with no risk of false-negative results.