To determine the prevalence of hemolytic uremic syndrome (HUS) among pediatric patients admitted to Assiut University Children's Hospital, and to describe the demographic, clinical, and laboratory characteristics of the affected population.

Hemolytic uremic syndrome (HUS) is a rare but serious condition characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. [1] Two main subtypes of HUS are recognized. The majority of pediatric cases are classified as typical HUS, most frequently associated with Shiga toxin-producing Escherichia coli (STEC) infection. In contrast, atypical HUS (aHUS) is less common, accounting for approximately 5-10% of cases, and is linked to dysregulation of the complement system. The clinical course and prognosis differ significantly between these subtypes.[2].

Understanding the prevalence of HUS is critical for early recognition and timely intervention, especially in resource-limited settings. [3] Complications of HUS can be severe and include neurological manifestations, hypertension, persistent renal impairment, and in some cases, death. Early diagnosis and supportive care are critical for improved outcomes [4].

Local factors such as water safety, sanitation, access to early antibiotics, and public health surveillance greatly affect the observed prevalence. [5] The management of typical HUS caused by STEC is generally supportive. [6] For aHUS, early treatment is crucial to avoid end-stage renal disease (ESRD) and mortality. The cornerstones of treatment for aHUS are first-line therapy with eculizumab [7]

Inclusion Criteria:

• Patients aged below 18 years at the time of diagnosis.
• Confirmed diagnosis of HUS based on the clinical triad (microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury).

Exclusion Criteria:

• Patients aged 18 years or above at the time of diagnosis.
• Incomplete or missing medical records that do not confirm the diagnosis.

Pediatric patients (aged <18 years) who were diagnosed with hemolytic uremic syndrome (HUS) and admitted to Assiut University Children's Hospital during the period from 1 October 2025 to 30 September 2026.