Nephrotic Syndrome

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).

⭐ 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.

⭐ 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.