1. Heavy protein loss in urine (proteinuria)
2. Low blood albumin (hypoalbuminemia)
3. Edema (swelling)
4. Often high lipids (hyperlipidemia)

1) What is happening pathophysiologically

• Albumin loss in urine lowers plasma oncotic pressure
• Fluid shifts into tissues causing edema
• Effective circulating volume may fall, activating RAAS and ADH, worsening sodium/water retention
• Liver increases synthesis of lipoproteins and clotting factors, contributing to hyperlipidemia and thrombosis risk
• Urinary loss of immunoglobulins and complement factors contributes to infection risk

2) Epidemiology in children

• Most common age: 2 to 6 years
• Boys are slightly more affected in early childhood
• Most pediatric cases are primary (idiopathic) and are usually steroid-sensitive
• Most common histology in children: Minimal change disease (MCD)

3) Classification

A) By cause

• Minimal change disease (most common)
• Focal segmental glomerulosclerosis (FSGS)
• Membranous nephropathy (less common in younger children)

• Infections (hepatitis B/C, HIV, malaria, others)
• Systemic disease (SLE, vasculitis)
• Drugs (NSAIDs, interferon, etc.)
• Malignancy (rare in pediatrics)
• Congenital/genetic forms (podocyte gene defects, e.g., NPHS1/NPHS2)

B) By response to steroids

• Steroid-sensitive nephrotic syndrome (SSNS)
• Steroid-resistant nephrotic syndrome (SRNS)

C) By relapse pattern (in SSNS)

• Infrequently relapsing
• Frequently relapsing
• Steroid-dependent

4) Clinical presentation

• Periorbital puffiness (often morning, may progress to generalized edema)
• Pedal/scrotal/labial edema
• Ascites, pleural effusion in severe cases
• Weight gain
• Fatigue, reduced appetite
• Frothy urine
• Blood pressure can be normal or elevated
• Gross hematuria is less typical in pure MCD and suggests alternative diagnosis when prominent

5) Diagnostic approach

Core diagnostic tests

• Urinalysis: 3+ or 4+ protein; usually bland sediment in MCD
• Spot urine protein/creatinine ratio (UPCR) markedly elevated
• Serum albumin low
• Lipids elevated (cholesterol, triglycerides)
• Creatinine/BUN to assess kidney function
• Electrolytes

Additional baseline tests

• CBC
• LFTs
• Complement (C3/C4) if atypical features
• ANA, anti-dsDNA, hepatitis serology, HIV if secondary cause suspected
• TB screen before certain immunosuppressants
• Kidney ultrasound when indicated

When to suspect atypical nephrotic syndrome (and broaden workup / consider biopsy early)

• Age <1 year or older child/adolescent at first presentation
• Persistent hypertension
• Persistent gross hematuria
• Low complement
• Reduced kidney function not due to hypovolemia
• Systemic symptoms (rash, arthritis, purpura)
• Steroid resistance

6) Kidney biopsy: when generally indicated in pediatrics

• Steroid resistance
• Atypical features listed above
• Suspected secondary disease
• Declining GFR
• Before certain second-line therapies depending on local protocol

7) Treatment

A) Initial episode (typical idiopathic childhood NS)

• Daily induction phase followed by alternate-day phase
• Exact regimen varies by guideline and center protocol
• Most children with MCD remit within weeks

• Salt restriction (especially with edema)
• Fluid moderation if severe edema/hyponatremia
• Diuretics for significant edema (carefully)
• Albumin infusion + loop diuretic in severe intravascular depletion/tense edema (specialist-guided)
• Vaccination review and infection prevention
• Gastric and bone protection only when indicated by risk profile and duration of steroids

B) Relapse treatment

• Urine dipstick monitoring at home helps early detection
• Standard steroid relapse regimen usually shorter than initial course
• Manage triggers (viral infections, adherence issues)

C) Frequently relapsing / steroid-dependent disease

• Cyclophosphamide
• Levamisole (in some regions)
• Calcineurin inhibitors (cyclosporine, tacrolimus)
• Mycophenolate mofetil
• Rituximab (selected cases)

D) Steroid-resistant nephrotic syndrome (SRNS)

• Requires nephrology-led evaluation, usually kidney biopsy and genetic testing
• May respond to calcineurin inhibitors in a subset
• Higher risk of progression to chronic kidney disease
• RAAS blockade (ACE inhibitor/ARB) often used to reduce proteinuria (with monitoring)

8) Major complications

1. Infections
   • Spontaneous bacterial peritonitis, cellulitis, pneumonia, sepsis, varicella severity
   • Due to urinary immunoglobulin loss + immunosuppressive therapy
2. Thromboembolism
   • Renal vein thrombosis, DVT, pulmonary embolism, cerebral venous thrombosis
   • Risk rises with severe hypoalbuminemia, hemoconcentration, central lines, immobility
3. Hypovolemia / AKI
   • Overdiuresis, severe third-spacing, sepsis, nephrotoxic exposure
4. Dyslipidemia
5. Drug toxicities
   • Steroids: obesity, hypertension, growth effects, cataracts, glucose intolerance, behavior changes
   • CNI: nephrotoxicity, hypertension, cosmetic effects (cyclosporine), diabetes risk (tacrolimus)
   • Cyclophosphamide: gonadal toxicity risk, cytopenias

9) Monitoring and follow-up

• Home urine protein dipsticks (daily during risk periods)
• Weight, edema, blood pressure
• Growth parameters
• Serum creatinine, albumin, lipids, electrolytes
• Drug-specific monitoring:
  • CNI trough levels + renal function
  • CBC/LFTs for selected agents
• Adherence checks and relapse diary
• Psychosocial and school support

10) Prognosis

• SSNS/MCD: generally excellent long-term renal prognosis; many children eventually have fewer relapses and achieve sustained remission
• FRNS/SDNS: morbidity from relapses and steroid burden, but renal survival often good with proper steroid-sparing strategies
• SRNS/FSGS: less favorable; higher CKD progression risk
• Early response to steroids is one of the strongest prognostic indicators

11) Practical red flags needing urgent evaluation

• Fever in nephrotic child (possible serious infection)
• Severe abdominal pain (SBP, thrombosis, hypovolemia)
• Respiratory distress (effusion, pulmonary edema, PE)
• Oliguria/anuria
• Altered mental status, severe headache, focal deficits (CNS thrombosis/hypertensive emergency)
• Marked dehydration signs despite edema

12) Parent counseling points

• Explain relapse-prone but often treatable course
• Teach urine dipstick technique and action plan
• Salt intake guidance
• Seek care urgently for fever, abdominal pain, breathing difficulty, reduced urine
• Discuss medication side effects and adherence
• Keep vaccinations updated (timing with immunosuppressive therapy per clinician)

1. a guideline-style steroid regimen framework (initial + relapse),
2. a comparison table: SSNS vs SRNS vs atypical NS,
3. a one-page exam revision note for pediatrics.