Nephrotic Syndrome

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Intro & Pathophysiology - Leaky Kidney Saga

  • Nephrotic Syndrome (NS): Triad/Tetrad:
    • Massive Proteinuria: > 40 mg/m²/hr or Urine Protein:Creatinine ratio > 2 mg/mg.
    • Hypoalbuminemia: < 3 g/dL.
    • Generalized Edema.
    • Hyperlipidemia (often present).
  • Pathophysiology: "Leaky" Glomerular Filtration Barrier (GFB).
    • Podocyte injury (foot process effacement) is key.
    • Loss of GFB charge/size selectivity → heavy albuminuria.
    • Hypoalbuminemia → ↓ plasma oncotic pressure → edema.
    • Hepatic lipoprotein synthesis ↑ → hyperlipidemia.
  • Types: Primary (idiopathic, e.g., MCD, FSGS) vs. Secondary (systemic disease, infection, drugs). Podocyte foot process effacement in nephrotic syndrome

⭐ Minimal Change Disease (MCD) is the most common cause of nephrotic syndrome in children (80-90% of cases).

Clinical Features - Puffy Kid Parade

  • Massive Edema: Cardinal sign. Soft, pitting, generalized.
    • Initial: Periorbital (esp. morning), facial puffiness.
    • Progresses to: Dependent areas (ankles, legs, scrotum/labia), ascites, pleural effusion.
  • Frothy Urine: Due to severe proteinuria.
  • Systemic: Anorexia, malaise, irritability, abdominal distension/pain.
  • BP: Typically normal; occasionally transient hypertension.
  • Urine output: May be ↓ (oliguria) during severe edema. Child with periorbital edema from nephrotic syndrome

⭐ Periorbital edema, especially prominent in the morning and preceding peripheral edema, is a classic early sign.

Diagnostic Workup - Sleuthing Syndrome Clues

  • Renal Biopsy If:
    • Age <1 yr or >12 yrs.
    • Atypical: Hematuria, HTN, ↓GFR, low C3.
    • Steroid-resistant.

⭐ Diagnostic hallmark: Nephrotic-range proteinuria is defined as > 40 mg/m²/hour or a spot urine protein/creatinine ratio > 2-3 mg/mg (or > 200-300 mg/mmol).

Management - Steroid Power Play

  • Initial Therapy (First Episode):
    • Prednisolone: 2 mg/kg/d (max 60 mg) x 6 wks.
    • Then: 1.5 mg/kg alt. days x 6 wks, then taper.
  • Key Definitions:
    • Remission: Urine alb nil/trace x 3 days.
    • Relapse: Urine alb ≥2+ x 3 days.
    • FRNS: ≥2 relapses/6mo or ≥4/12mo.
    • SDNS: Relapse on taper / within 2 wks post-steroid.
    • SRNS: No remission after 8 wks daily prednisolone.
  • Relapse:
    • Prednisolone 2 mg/kg/d till remission, then 1.5 mg/kg alt. days x 4 wks, taper.

80-90% of Minimal Change Disease cases achieve remission with corticosteroids.

Complications & Prognosis - Dodging Danger Zones

  • Infections: ⚠️ SBP, cellulitis. Due to ↓IgG.
  • Thromboembolism: DVT, PE, RVT. Loss of antithrombin III.
  • Hyperlipidemia: ↑ Cholesterol, triglycerides.
  • AKI: From hypovolemia.
  • Steroid Side Effects: Growth failure, cushingoid.
  • Prognosis:
    • MCD: Excellent (>90% steroid-sensitive); relapses common.
    • FSGS: Guarded (~50% ESRD).

⭐ Patients with nephrotic syndrome are at high risk of infections, especially Spontaneous Bacterial Peritonitis (SBP) caused by encapsulated organisms like Streptococcus pneumoniae.

High‑Yield Points - ⚡ Biggest Takeaways

  • Characterized by massive proteinuria (>40 mg/m²/hr or UPC >2), hypoalbuminemia (<2.5 g/dL), generalized edema, and hyperlipidemia.
  • Minimal Change Disease (MCD) is the predominant cause in children (>80%), typically idiopathic.
  • Majority of MCD cases are steroid-sensitive, showing good response to initial corticosteroid therapy.
  • Major complications include serious infections (especially Spontaneous Bacterial Peritonitis due to S. pneumoniae) and thromboembolic events.
  • Renal biopsy is usually reserved for atypical features (e.g., age <1 year or >12 years, persistent hypertension, gross hematuria) or steroid resistance.
  • Look for frothy urine and periorbital edema as classic early presenting signs in children.
  • Management focuses on inducing remission with steroids, managing edema, and preventing complications.

Practice Questions: Nephrotic Syndrome

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An 8-year-old child presents with hematuria 5 days after a throat infection. What is the most likely diagnosis?

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Flashcards: Nephrotic Syndrome

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_____ is the most common cause of nephrotic syndrome in children

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_____ is the most common cause of nephrotic syndrome in children

Minimal change disease (lipoid nephrosis)

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