Nephrotic Syndrome vs. Acute Kidney Injury (AKI)
Distinguishing these renal presentations is a core competency for pediatrics and internal medicine boards.
1. Nephrotic Syndrome (The “4 Pillars”)
- Massive Proteinuria: Urine protein > 50 mg/kg/day or spot UPCR > 2.
- Hypoalbuminemia: Serum albumin < 2.5 g/dL.
- Edema: Due to decreased oncotic pressure.
- Hyperlipidemia: Secondary to compensatory hepatic protein synthesis.
2. Acute Kidney Injury (AKI)
| Type | High-Yield Mechanism |
|---|---|
| Prerenal | Hypovolemia; FeNa < 1%. |
| Intrinsic | ATN/AIN; FeNa > 2%. |
| Postrenal | Obstruction (e.g., PUV, stones). |
NEET PG Hint: For Nephrotic Syndrome, remember Minimal Change Disease (MCD) is the most common cause in children and is steroid-responsive. For AKI, remember that the Fractional Excretion of Sodium (FeNa) is the key differentiator between prerenal and intrinsic causes.