SHM Converge Scientific Abstract ePoster Gallery-A Rare Presentation of C3 Glomerulopathy: Diagnostic Challenges and Therapeutic Considerations

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This case report describes a rare presentation of C3 glomerulopathy (C3G), a complement-mediated kidney disease that affects about 1–2 people per million. C3G is caused by dysregulation of the alternative complement pathway and often resembles post-infectious glomerulonephritis (PIGN) at first presentation. The report highlights that viral infections, including COVID-19, may trigger disease onset.<br /><br />A 28-year-old man developed edema, hematuria, nephrotic-range proteinuria, acute kidney injury, and low C3 after a recent COVID-19 infection. Because his complement levels remained low longer than expected, a renal biopsy was performed. Light microscopy showed glomerular hypercellularity, immunofluorescence demonstrated dominant granular C3 deposition, and electron microscopy revealed mesangial and subendothelial electron-dense deposits, confirming C3 glomerulonephritis (C3GN).<br /><br />He was initially managed as presumed PIGN with supportive care. After biopsy confirmed C3GN, treatment was escalated to corticosteroids and mycophenolate mofetil, followed later by the complement inhibitor iptacopan. This led to marked improvement in proteinuria and kidney function.<br /><br />The discussion emphasizes that PIGN and C3GN can look very similar clinically and on biopsy, but persistent hypocomplementemia beyond 6–8 weeks should raise suspicion for C3GN. KDIGO guidelines support kidney biopsy in atypical or prolonged cases. Key differences include persistent low C3, C3-dominant immunofluorescence, and mesangial/intramembranous deposits in C3GN versus self-limited disease and subepithelial humps in PIGN.<br /><br />Overall, the report underscores the importance of early recognition of C3GN, especially when presumed PIGN does not resolve, because timely diagnosis can change therapy and improve outcomes.

Asset Subtitle

Jordyn Richardson

Meta Tag

Author List Biju Cherian, Jordyn Richardson

Category Clinical Vignettes

Concept C3 Glomerulopathy

Concept C3 Dominant Deposition

Concept Alternative Complement Pathway

Concept Complement Dysregulation

Concept Hypocomplementemia

Distinguished Non-Finalist

Presenter Organization Burrell College of Osteopathic Medicine

Presenting Author Jordyn Richardson

Track Adult

Keywords

C3 glomerulopathy

C3 glomerulonephritis

alternative complement pathway

post-infectious glomerulonephritis

COVID-19 infection

hypocomplementemia

renal biopsy

proteinuria

mycophenolate mofetil

iptacopan

C3 Glomerulopathy

C3 Dominant Deposition

Alternative Complement Pathway

Complement Dysregulation

Hypocomplementemia