12-month-old with red urine 1-3 days after a URI most likely has which condition?

12-month-old with red urine 1-3 days after a URI most likely has which condition?

• A. IgA nephropathy
• B. PSGN
• C. Henoch-Schönlein purpura
• D. Alport syndrome

Answer: (A)

Red urine that appears within days of a mucosal infection points to IgA nephropathy. This condition involves deposition of IgA-containing immune complexes in the glomerular mesangium after a respiratory infection, causing acute hematuria that tracks with the URI. In a 12-month-old, the pattern remains diagnostic: hematuria occurring concurrently with or shortly after the URI suggests IgA nephropathy. Post-streptococcal glomerulonephritis would typically show hematuria about 1–3 weeks after a streptococcal infection and often comes with edema, hypertension, and low complement levels. Henoch-Schönlein purpura features a purpuric rash (often with abdominal pain and joint symptoms) alongside possible kidney involvement, but the hallmark is the vasculitic rash. Alport syndrome causes persistent hematuria from a hereditary nephritis and is associated with progressive hearing loss, not an immediate post-infectious hematuria pattern.

Red urine that appears within days of a mucosal infection points to IgA nephropathy. This condition involves deposition of IgA-containing immune complexes in the glomerular mesangium after a respiratory infection, causing acute hematuria that tracks with the URI. In a 12-month-old, the pattern remains diagnostic: hematuria occurring concurrently with or shortly after the URI suggests IgA nephropathy.

Post-streptococcal glomerulonephritis would typically show hematuria about 1–3 weeks after a streptococcal infection and often comes with edema, hypertension, and low complement levels. Henoch-Schönlein purpura features a purpuric rash (often with abdominal pain and joint symptoms) alongside possible kidney involvement, but the hallmark is the vasculitic rash. Alport syndrome causes persistent hematuria from a hereditary nephritis and is associated with progressive hearing loss, not an immediate post-infectious hematuria pattern.