# Paroxysmal nocturnal hemoglobinuria masquerading as hemolytic uremic syndrome: a Case Report

## TL;DR

A rare blood disorder called PNH was mistaken for another condition called HUS due to similar symptoms, but was correctly diagnosed after a kidney biopsy.

## Contribution

This case highlights the diagnostic challenge of distinguishing PNH from HUS in patients without a known blood disorder history.

## Key findings

- The patient initially diagnosed with aHUS was later confirmed to have PNH through biopsy and tests.
- Renal function and anemia improved after appropriate treatment for PNH.
- PNH and HUS share similar symptoms, making differential diagnosis difficult without detailed testing.

## Abstract

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired disorder of intravascular hemolysis caused by a somatic mutation in the gene responsible for glycosylphosphatidylinositol (GPI)-anchored complement regulatory proteins. This mutation leads to the production of abnormal blood cell clones lacking CD55 and CD59. PNH can result in renal damage. The challenge of early identification and diagnosis leads to misdiagnosis as other intravascular hemolytic conditions. This paper presents a case that began with fever, diarrhea, and acute renal failure, initially misdiagnosed as atypical hemolytic uremic syndrome (aHUS) but later confirmed as PNH through renal biopsy and related diagnostic tests. After treatment, the patient’s renal function recovered, and anemia improved. Intravascular hemolysis is a prominent feature common to both PNH and HUS. They exhibit similar clinical manifestations, which pose a challenge for differential diagnosis. Unlike previous reports, the patient in this case denied any history of hematologic disorders, which made the diagnosis more challenging.