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Kidney Week

Abstract: TH-PO694

EXT-1 Membranous Glomerulonephropathy

Session Information

Category: Glomerular Diseases

  • 1402 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Pabon-Vazquez, Elizabeth, Augusta University Medical College of Georgia, Augusta, Georgia, United States
  • Kosuru, Vatsalya, Augusta University Medical College of Georgia, Augusta, Georgia, United States
Introduction

Membranous nephropathy is one of the most common causes of nephrotic syndrome in adults.The most common etiology is autoimmune condition and identification of pertinent antigens could help in the management of the disease.

Case Description

This is the case of a 33y/o male with past medical history of chronic inflammatory demyelinating polyneuropathy and recurrent pulmonary embolism on apixaban.Patient presented to emergency department complaining of worsening pleuritic chest pain and shortness of breath of one day of evolution.He was also tachycardic,tachypneic and had bilateral lower extremity edema.Laboratory evaluation was remarkable for >600protein and 0-3RBCs on urine dipstick.Renal panel showed creatinine of 1.27mg/dL and albumin of 1.7g/dL.The patient was admitted for recurrent unprovoked pulmonary embolism despite being on anticoagulation therapy and nephrotic syndrome.Initial workup for nephrotic syndrome reported 24-hour urine protein of 20,570mg.Further work up was negative for diabetic disease,hepatitis panel,HIV panel,complements,PLA2R antibodies and lupus nephritis.However, serologic markers ANA,RNP70 Ab and U1 RNP Ab were positive consistent with mixed connective tissue disease.During hospitalization, the patient developed an acute kidney injury with creatinine elevated to 2.65mg/dL, and renal biopsy was performed.Kidney biopsy showed acute tubular injury and exostosin-1 associated membranous glomerulopathy.The patient was treated with two doses of 1g rituximab,prednisone,and losartan.At subsequent clinic follow up, patient's spot urine protein-creatinine ratio was improved to 3.4g. Renal function is stable with creatinine of 1.13mg/dL and albumin improved to 2.3g/dL.

Discussion

Exostosin 1 and 2 are novel proteins seen in secondary membranous nephropathy associated with autoimmune diseases, especially lupus nephritis.Our patient's case is unique as his serology is positive for mixed connective tissue disease with no extra-renal manifestations and this is the first case reported of the association of MN with mixed connective tissue disease.Due to rarity of disease and lack of standard therapy we have opted for rituximab treatment based on literature review.After the initial course of rituximab treatment,our patient showed significant improvement in proteinuria to sub-nephrotic range.He is currently on medical management with losartan.