Abstract: SA-PO814
C3 Glomerulonephritis in a Child with Elevated Anti-streptolysin O (ASO) Titer
Session Information
- C3G, TMA, MGRS, Amyloidosis, and More
October 26, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Rosario-Falero, Jessica M., Louisiana State University, Baton Rouge, Louisiana, United States
- Yosypiv, Ihor V., Tulane University School of Medicine, New Orleans, Louisiana, United States
Introduction
C3 glomerulopathy in children is rare with an estimated incidence of 1-4 cases per million population. Most children with C3 glomerulopathy have C3 glomerulonephritis (C3GN). C3GN carries a poor kidney prognosis, with a median time to kidney failure of around 10 years from diagnosis. We report the case of a pediatric patient presenting with features of acute glomerulonephritis (GN) and elevated ASO titer who was promptly diagnosed with C3GN.
Case Description
A previously healthy 14 y.o. male presented to his pediatrician with dark urine color, facial and lower extremity swelling, and headache for 3 days. Family history was non-contributory. Blood pressure was elevated. Laboratory workup showed unremarkable CBC, normal creatinine-based eGFR of 105 ml/min/1.73m2, serum albumin 3.0 mg/dL, normal C4 and reduced C3 (23 mg/dL; ref. range 80-173) complement levels, elevated ASO titer (563 IU/ml; ref. range <350), normal CRP and ESR. Urinalysis had 2+ protein, 3+ blood, 51-99 WBC, >100 RBC and spot protein/creatinine ratio 4.0 mg/mg. Physical exam on admission showed BP at stage 2 hypertension level, mild facial and 2+ pitting edema in lower extremities, and mild ascites. Although presentation was consistent with acute postinfectious GN (APIGN), presence of nephrotic range proteinuria prompted us to perform renal biopsy on admission. Histology showed 4+ staining for C3, +/-peripheral granular staining for C1q, +/- mesangial granular staining for IgM, with no staining for IgG or IgA. EM showed endothelial swelling occluding glomerular capillary lumens, subendothelial electron dense deposits, basement membrane reduplication and extensive foot process fusion. Diagnosis of C3GN was made. Expanded infectious workup was negative. Complement studies showed: normal Factor H auto-antibody, negative C3, CD46, CFB, CFD, CFH, CFHR2, CFHR5, CFI gene sequence panel and positive C3 Nephritic factor of 13.5 (ref. range 0.0 unit/ml). Therapy with mycophenolate mofetil, oral prednisone and lisinopril was initiated.
Discussion
This case emphasizes the need to consider C3GN in a child presenting with findings consistent with APIGN. As therapies of APIGN and C3GN differ, establishing correct diagnosis promptly is critical. In this case, timely performance of kidney biopsy established correct diagnosis, enabled to initiate in-depth evaluation of alternative complement pathway (ACP) and targeted therapy.