## Distinguishing PSGN from ARF ### Clinical Context Both PSGN and ARF are non-suppurative sequelae of Group A Streptococcus (GAS) infection. However, they differ fundamentally in organ involvement, latency, and clinical presentation. ### Key Discriminating Features | Feature | PSGN | ARF | |---------|------|-----| | **Primary organ affected** | Kidney (glomerulus) | Heart (myocardium, valves, joints) | | **Latency period** | 1–3 weeks (post-pharyngitis) | 2–3 weeks (post-pharyngitis) | | **Cardinal finding** | Hematuria, proteinuria, hypertension, edema | Migratory polyarthritis, carditis, murmur | | **ASO titre** | Elevated (both conditions) | Elevated (both conditions) | | **Urine findings** | RBC casts, dysmorphic RBCs | Normal | | **Cardiac involvement** | Absent or mild (not primary) | Prominent (pancarditis) | **Key Point:** PSGN presents with **renal-specific findings** (hematuria, proteinuria, hypertension, periorbital edema), whereas ARF presents with **cardiac and joint manifestations** (new murmur, migratory arthritis, carditis). ### Why Option 2 is Correct Hematuria with proteinuria, hypertension, and edema are pathognomonic for acute glomerulonephritis and distinguish PSGN from ARF, which manifests with carditis and arthritis instead. **Clinical Pearl:** PSGN is self-limited and resolves in weeks to months; ARF can cause permanent valvular damage (mitral stenosis, aortic regurgitation) and requires long-term penicillin prophylaxis. **High-Yield:** Remember the acronym **PSGN = Pee (hematuria) + Pressure (hypertension) + Puffiness (edema)**, whereas **ARF = Arthritis + Rheumatic heart disease**.
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