# A Severe Form of Atypical Hemolytic Uremic Syndrome in a Two-Year-Old Girl: A Case Report

## TL;DR

A two-year-old girl with a severe form of atypical hemolytic uremic syndrome recovered after treatment with plasmapheresis and rituximab.

## Contribution

This case report highlights the importance of early intervention in atypical HUS despite limited genetic testing capabilities.

## Key findings

- The patient showed clinical improvement after plasmapheresis and rituximab treatment.
- Atypical HUS in young children can have a severe clinical course requiring prompt management.
- Timely intervention can prevent progression to chronic kidney disease even without genetic confirmation.

## Abstract

Hemolytic uremic syndrome (HUS) is a prevalent cause of severe acute kidney injury in children, often leading to chronic renal damage. It is characterized by thrombotic microangiopathy (TMA), which represents a triad of microangiopathic hemolytic anemia, thrombocytopenia, and renal impairment. The choice of treatment and management strategies depends primarily on the underlying etiology. We present the case of a two-year-old girl diagnosed with rapidly progressive glomerulonephritis accompanied by hypertension necessitating renal replacement therapy. Initial laboratory findings indicated positive antinuclear antibodies, prompting immunosuppression and renal biopsy, revealing TMA with minimal chronicity changes. The treatment involved plasmapheresis and a single dose of injection rituximab, resulting in clinical recovery with an improved glomerular filtration rate. Since the anti-complement factor H antibody result was negative, the genetic etiology of atypical HUS was considered. The patient was discharged with favorable outcomes, including normal urine output and the absence of edema. This case concludes that young children with atypical HUS may present with a severe clinical course necessitating early intervention. The lack of genetic analysis facilities in severe cases should not hinder the timely initiation of plasmapheresis to prevent further injury and progression to chronic kidney disease.