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Abstract: SA-PO229

Monoclonal Gammopathy of Renal Significance (MGRS): An Alternative Pathway to C3 Glomerulonephritis (C3GN)

Session Information

Category: Onconephrology

  • 1700 Onconephrology


  • Magliulo, Eric, University of Nebraska Medical Center, Omaha, Nebraska, United States
  • Aslam, Saher, University of Nebraska Medical Center, Omaha, Nebraska, United States
  • Foster, Kirk W., University of Nebraska Medical Center, Omaha, Nebraska, United States
  • Ravipati, Prasanth, University of Nebraska Medical Center, Omaha, Nebraska, United States
  • Naranjo, Felipe Sebastian, University of Nebraska Medical Center, Omaha, Nebraska, United States

C3 glomerulonephritis (C3GN) is characterized by dysregulation of the alternative complement pathway and is commonly accompanied by a monoclonal gammopathy in older patients. These associated paraproteins are now increasingly recognized as the underlying drivers of complement dysregulation in many cases, which has important implications regarding treatment.

Case Description

An 86 year old male with a past medical history of atrial fibrillation and congestive heart failure presented with a ground level fall, sustaining a small subdural hematoma. On arrival, he was hypotensive secondary to atrial fibrillation with a slow ventricular response requiring an implantable pacemaker. He was hypoxic due to pulmonary edema seen on imaging. Labs showed a rise in serum creatinine to 3.89 mg/dl from a baseline of 1.0 mg/dl. Urine dipstick showed 3+ hematuria and a urine protein to creatinine ratio was measured at 2 g/g. He was presumed to have acute tubular injury and received intravenous diuretics with improvement in hypoxia. Nephrology was consulted to assist with diuretic management. Manual urine microscopy was performed which revealed numerous dysmorphic red blood cells (RBCs). Serologic testing was unremarkable except for a monoclonal IgG kappa paraprotein identified on immunofixation. We ultimately decided to pursue a kidney biopsy which revealed a C3 dominant crescentic glomerulonephritis with mesangial proliferation and rare mesangial electron dense deposits. The bone marrow biopsy showed hypercellularity with a polyclonal plasmacytosis. He was diagnosed with C3GN with monoclonal gammopathy and was started on treatment with bortezomib and steroids.


We present a challenging case of acute kidney injury in an elderly male. Ultimately, the finding of dysmorphic RBCs on urine microscopy informed our decision to pursue a kidney biopsy, leading to a diagnosis of C3GN with monoclonal gammopathy. Recent evidence suggests that in many cases, dysregulation of the alternative pathway is driven by a monoclonal paraprotein. Furthermore, treatment directed towards the underlying hematologic disease has shown promise in achieving a renal response. For this reason, we elected to pursue treatment targeting the underlying hematologic disorder.