A 25-year-old man presents with hematuria, red cell casts, and proteinuria of 1.8 g/day, 2 weeks after a sore throat. BP is 155/95 mmHg. Serum C3 is low, C4 is normal. ASO titer is elevated. What is the most likely diagnosis?
- A Post-streptococcal glomerulonephritis ✓
- B IgA nephropathy
- C Membranoproliferative glomerulonephritis
- D Lupus nephritis
Correct answer: A. Post-streptococcal glomerulonephritis
Explanation
Post-streptococcal glomerulonephritis (PSGN) classically presents 10–14 days after streptococcal pharyngitis with the nephritic syndrome: hematuria with red cell casts, mild proteinuria, hypertension, and edema. Low C3 with normal C4 reflects activation of the alternate complement pathway, which is characteristic of PSGN. Elevated ASO titer confirms recent streptococcal infection. IgA nephropathy typically presents with synpharyngitic hematuria (concurrent with infection, not 2 weeks later).
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.