Time-Course of Platelets Count in Children with Hemolytic Uremic Syndrome. Data from the ItalKid-HUS Network.

Background Hemolytic uremic syndrome (HUS) related to Shiga toxin-producing Escherichia Coli (STEC) infection is a severe, life-threatening thrombotic microangiopathy (TMA). Endothelial damage causes platelet consumption and consequently platelet count is a key biomarker for monitoring disease activity. The present paper describes the time course of platelet count in a cohort of patients with STEC-HUS in order to provide references helpful in identifying subjects who divert from the expected course because complications. Methods All children treated at our Center with a well-established diagnosis of STEC-HUS during the period 2010–2025 were retrospectively enrolled and platelets count was recorded until discharge. The nadir of platelets count for each patient was used to align the results and investigate the time course towards platelets normalization. The cumulative percentage of platelets normalization was calculated on daily basis, together with the 10th centile of platelets count. Result During the 16 years under investigation, a total of 148 children were enrolled. The nadir of platelets count was 23,000/mm3 (IQR 14,000–39,000) on day 8 since the beginning of symptoms. By day 14 from the nadir, 100% of patients had reached a platelets count > 150.000/mm3. Conclusions Given that STEC-HUS is a self-limiting disease, the related TMA is expected to spontaneously cease within a defined time. If platelets count has a different course from the expected, the patient is likely to have complications that need to be actively searched for and treated accordingly (e.g. atypical HUS, disseminated intravascular coagulation or heparin induced thrombocytopenia).