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Kidney Week

Abstract: SA-PO801

An Unusual Case of Lupus-Associated Atypical Hemolytic Uremic Syndrome Presenting with Diffuse Alveolar Hemorrhage and Acute Renal Failure

Session Information

Category: Genetic Diseases of the Kidneys

  • 1202 Genetic Diseases of the Kidneys: Non-Cystic

Author

  • Theodoru, Andrea, Northside Hospital Inc, Atlanta, Georgia, United States
Introduction

Atypical hemolytic uremic syndrome (aHUS) is a rare genetic disease characterized by acute renal injury (AKI), thrombotic microangiopathy (TMA), and other end-organ damage. It occurs when genetic mutations alter complement regulatory proteins, most commonly complement factor H. As a diagnosis of exclusion, it presents a unique diagnostic challenge. Eculizumab, a monoclonal antibody against complement C5, is the treatment of choice for primary aHUS.

Case Description

A 43 year old male with past medical history of systemic lupus erythematosus, Grave’s disease, and hypertension presented to our institution with respiratory distress, hemoptysis, and subjective fevers. He had recently been treated with intravenous antibiotics after sustaining a cat bite. On presentation, he was profoundly hypoxic with elevated D-dimers, thrombocytopenia, and diffuse bilateral alveolar infiltrates. Patient was subsequently intubated, and serial bronchiolar lavage was consistent with diffuse alveolar hemorrhage (DAH). Renal function rapidly declined and lupus pneumonitis and nephritis were suspected; renal biopsy showed class III lupus nephritis. Pulse dose steroids and rituximab were initiated. Despite this, patient developed recurrent hemoptysis, worsening renal failure, and purpuric rash, which did not improve with plasmapheresis. In setting of markedly elevated D-dimers and LDH, thrombocytopenia, low haptoglobin, and peripheral smear revealing schistocytes, thombotic microangiopathy was suspected. Furthermore, markedly depressed complement levels pointed towards complement activation, likely triggered by his previous infection, resulting in adult onset atypical hemolytic uremic syndrome. Eculizumab was initiated and patient was eventually discharged to rehabilitation unit. Genetic testing revealed he was positive for aHUS with thrombomodulin gene mutation.

Discussion

This is an unusual case of lupus associated aHUS, likely triggered by infection caused by cat bite which triggered alternate complement pathway causing DAH. Atypical HUS presenting as DAH is extremely rare, and this case pointed towards lung restricted TMA. It is imperative that aHUS remains on the differential for patients with AKI and suspected TMA, as recognition of this diagnosis drastically alters management. Timely management lowers morbidity and mortality in aHUS.