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Kidney Week

Abstract: PO0185

Hemoglobin Cast Nephropathy in Rifampin-Induced Hemolytic Anemia

Session Information

  • AKI Mechanisms - 2
    October 22, 2020 | Location: On-Demand
    Abstract Time: 10:00 AM - 12:00 PM

Category: Trainee Case Report

  • 103 AKI: Mechanisms

Authors

  • Mahmud, Saqib, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Dernell, Carl Scott, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Bal, Naveet, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Koratala, Abhilash, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Gallan, Alexander James, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Sturgill, Daniel Allen, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
Introduction

Hemoglobin released after intravascular hemolysis causes acute kidney injury (AKI) by various mechanisms including hemoglobin cast nephropathy. This can resemble other causes of AKI such as acute tubular necrosis, acute interstitial nephritis (AIN) and thrombotic microangiopathy (TMA). Few studies have demonstrated immunohistochemically-proven hemoglobin casts on kidney biopsy associated with intravascular hemolysis. Below is a case of Rifampin-induced hemolysis associated hemoglobin cast nephropathy.

Case Description

A 64-year-old female with recurrent pulmonary Mycobacterium Avium Complex (MAC) infection treated with Rifampin, Ethambutol and Azithromycin presented with nausea and vomiting two weeks after starting therapy. Physical exam was remarkable for small purpuric lesions on the back. Labs showed a serum creatinine of 6.6 mg/dL, BUN 66 mg/dL, hemoglobin 11.1 g/dL and platelets 9,000/uL. Haptoglobin was normal. LDH was elevated at 507 units/L. A direct antibody test was negative. Urinalysis showed large blood and microscopy showed 2-5 RBCs per hpf and dark granular casts. Renal ultrasound was unremarkable. Plasma exchange was initiated for possible TMA but discontinued when ADAMTS13 level returned normal.
On day four, serum creatinine was 8.1 mg/dL. She received methylprednisolone 120 mg daily for three days due to concern for possible Rifampin induced AIN. A kidney biopsy was planned and hemodialysis was performed to optimize platelet function. Kidney biopsy demonstrated intratubular pigmented casts that were strongly positive for hemoglobin A immunohistochemical stain confirming the diagnosis of hemoglobin cast nephropathy [Figure 1].
She received supportive care with kidney function gradually improving. Creatinine was 2.87 mg/dL on discharge and 1.18 mg/dL four weeks later.

Discussion

Hemoglobin cast nephropathy is a rare diagnosis and requires high index of suspicion in patients with hemolysis and AKI. Diagnosis is multifaceted requiring a clinical history, exam, lab workup and most importantly, a kidney biopsy.