A 9-year-old boy had periorbital edema, tea-colored urine, and low C3 following impetigo. Six months later he remains hypocomplementemic with persistent hematuria and new cryoglobulin-like symptoms. The persistence of low C3 beyond 8 to 12 weeks most strongly suggests:

• A Resolving post-streptococcal glomerulonephritis
• B Minimal change disease
• C Thin basement membrane disease
• D Membranoproliferative glomerulonephritis ✓

Explanation

In post-streptococcal glomerulonephritis, serum C3 falls during the acute phase and returns to normal within 6 to 8 weeks even while urinary abnormalities may persist. Hypocomplementemia persisting beyond 8 to 12 weeks points instead to MPGN (including dense deposit disease), lupus nephritis, or cryoglobulinemic GN. Thin basement membrane disease and minimal change disease are non-inflammatory entities with normal serum complement, so neither explains persistent C3 depression.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.