Case Report: Neonatal Unexplained HUS Treated With Complement Inhibitor Eculizumab.

Area of Science:

• Pediatric Nephrology
• Neonatology
• Hematology

Background:

• Neonatal Hemolytic Uremic Syndrome (HUS) is rare and often misdiagnosed as perinatal asphyxia due to similar presentations.
• Differentiating neonatal HUS from other conditions in the early postnatal period is clinically challenging.
• This case highlights a potential new subtype of neonatal HUS triggered by hypoxic-ischemic events.

Observation:

• A 35-week preterm infant presented with respiratory distress, hypotension, and acidosis, initially managed with blood transfusion.
• The infant subsequently developed renal failure, hematuria, hemobilia, thrombocytopenia, and coagulopathy refractory to transfusions.
• Laboratory findings included non-measurable haptoglobin, schistocytes, low complement factors (C3, C4, B), and increased factor Bb, supporting HUS diagnosis.

Findings:

• A single dose of Eculizumab was administered on day 9 of life, leading to clinical improvement.
• No genetic mutations associated with atypical HUS were identified in the patient.
• The infant was discharged with improving renal function, although cholestasis emerged as a potential side effect of Eculizumab.

Implications:

• Neonatal HUS should be suspected in infants presenting with hemolytic anemia, thrombocytopenia, hematuria, and renal failure.
• Eculizumab is a potential first-line therapy for neonatal HUS, with discontinuation considered if no genetic mutation is found and the patient improves.
• Cholestasis may present as a side effect of Eculizumab in very young patients.