A 6-year-old child presents with gross hematuria (cola-colored urine), periorbital edema, and hypertension 1 week after a throat infection. Serum C3 is 52 mg/dL (low). ASOT is 800 IU/mL. Urine shows RBC casts. What is the MOST IMPORTANT prognostic indicator of long-term outcome in this condition?

• A Severity of initial hypertension and presence of encephalopathy
• B Degree of proteinuria at presentation
• C Height of ASOT titer at presentation
• D Persistence of low C3 beyond 8–12 weeks after presentation ✓

Explanation

In post-streptococcal glomerulonephritis (PSGN), serum C3 is characteristically low at presentation due to activation of the alternate complement pathway. C3 should normalize within 6–8 weeks. Persistent hypocomplementemia beyond 8–12 weeks is an important red flag suggesting an alternative diagnosis (e.g., MPGN, SLE, or endocarditis-associated GN) with a worse prognosis. ASOT titer elevation confirms streptococcal infection but does not predict long-term outcome. Hypertension is important acutely but resolves. Proteinuria severity and ASOT height do not independently predict long-term renal outcome.

Reference: Ghai Essential Pediatrics, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.