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Kidney Week

Abstract: SA-PO851

Peripheral Neuropathy Leading to Diagnosis of ANCA-Associated Glomerulonephritis

Session Information

Category: Glomerular Diseases

  • 1401 Glomerular Diseases: From Inflammation to Fibrosis

Authors

  • Baker, Matthew Foster, Walter Reed National Military Medical Center, Bethesda, Maryland, United States
  • Malone, Laura, Walter Reed National Military Medical Center, Bethesda, Maryland, United States
  • Watson, Maura A., Walter Reed National Military Medical Center, Bethesda, Maryland, United States
  • Frankston, Amy J., Walter Reed National Military Medical Center, Bethesda, Maryland, United States
Introduction

ANCA-associated glomerulonephritis (GN) rarely presents with concomitant neurologic symptoms.

Case Description

A man in his seventies with type 2 diabetes mellitus and hypertension was admitted with 6-months of worsening extremity weakness and gait instability leading to a fall. Electromyelogram demonstrated diffuse demyelinating polyneuropathy. On admission, he had acute kidney injury (AKI) with serum creatinine 1.86 mg/dL (0.9 mg/dL at baseline). Urine microscopy showed acanthocytes, red blood cell casts, and dense granular casts. Renal biopsy demonstrated crescentic GN, acute interstitial nephritis with tubular necrosis, and a medium-sized artery occluded by thrombus. Direct immunofluorescence was positive for C3 and negative for IgG, IgM, IgA, C1q, fibrinogen, albumin, or kappa/lambda light chains. Perinuclear ANCA titer was elevated at 1:320. Anti-MPO antibodies were >8 units; anti-PR3 antibodies were elevated at 2.7 units. Diagnoses of ANCA-associated GN and microscopic polyangiitis (MPA) were made. He was treated with induction methylprednisolone and rituximab followed by prednisone taper. After treatment, renal function and extremity neuropathy symptoms improved. Serum creatinine improved from 2.42 mg/dL pre-treatment to 2.0 mg/dL at hospital discharge.

Discussion

The initial presentation of weakness and polyneuropathy is an unusual dominant symptom for MPA, which may have delayed recognition of renal involvement. He lacked other symptoms, including rash or sinusitis, that are often associated with systemic small-vessel vasculitis. C3 positivity on direct immunofluorescence does not rule out ANCA-associated GN despite its classic “pauci-immune” appearance. Plasmapheresis was considered due to concurrent AKI and autoimmune-mediated demyelinating polyneuropathy but was deferred due to lack of rapid renal failure or pulmonary hemorrhage. Immunosuppressive therapy directed at preserving kidney function also improved the neuropathy suggesting that these were both due to MPA. Recognition of unusual features of MPA-associated GN as demonstrated in this case aided diagnosis and should be considered in AKI cases with neurologic derangements.

The views expressed in this abstract are those of the author(s) and do not necessarily reflect the official policy of the Department of Defense or the U.S. Government.