Nephrotic Syndrome in Children : Definition, Etiology, Pathophysiology, Signs, Symptoms, Investigations, & Management
Definition
- Nephrotic Syndrome is a kidney disorder that presents with collection of characteristic symptoms.
Components
Five components
1. Massive proteinuria
Urine protein excretion > 40 mg/m2/hour
OR
Spot urine Protein/Creatinine > 2:1
OR
Urine dipstick : 3+ or 4+ urinary protein
2. Hypoalbuminemia
Serum albumin < 2.5 g/dl
3. Edema
- Periorbital puffiness more in the morning.
4. Hyperlipidemia
Serum cholesterol > 250 mg/dl
5. Hypercoagulability of blood
Types
Features | Primary (Idiopathic) | Secondary |
Category | Minimal change disease | Nephrotic syndrome with significant glomerular lesions ⇓ FSGS > MPGN |
Occurrence | 80% cases | 20% cases |
Age group | 2-6 year | <1 year, >10 year |
Symptoms | Hematuria, Hypertension ⇓ Rare to absent | Hematuria, Hypertension ⇓ Common |
Response | Excellent response to steroids | Variable response to steroids |
Pathophysiology
1. Massive proteinuria is because of damage to podocyte-slit membrane complex.
- Minimal change disease
T-cell activation
⇓
Reversible effacement of foot process of podocytes
- Other lesion
Inflammatory damage
⇓
Podocytes/slit membrane/GBM/ or all
- Congenital nephrotic syndrome
Absence of proteins forming slit membrane
2. Edema
- Major cause: Overfill hypothesis ⇒ Primary Na+/H2O retention (RSA axis activation)
- Minor/contributory/initiating cause: Underfill hypothesis ⇒ Decrease in oncotic pressure
Congenital nephrotic syndrome
- Onset < 3 months
- High mortality
Types
- Finnish type: NPHS-1 gene on chromosome 29 ⇒ Nephrin
- Classical SRNS: NPHS-2 gene on chromosome 1 ⇒ Podocin
Treatment
- Supportive
Complications
1. Infections
- Most common : Spontaneous bacterial peritonitis (SBP)
⇓
Most common cause in children: Pneumococcus
- Pneumonia
- Cellulitis
2. Thrombosis
Most common site
- Children: Cortical dural veins
- Adults: Renal vein
3. Growth retardation
4. Anemia
5. Rickets
6. Iatrogenic cushing syndrome
Relevant Terminologies
- Remission: When urine protein becomes nil or 1+ for 3 consecutive days.
- Relapse: Patient goes into remission initially but again develops urine protein excretion 3+ or 4+ for 3 consecutive days.
- Frequently relapsing nephrotic syndrome (FRNS): When more than 2 relapses in 6 months OR more than 3 relapses in one year.
- Steroid dependent nephrotic syndrome (SDNS): Patient stays in remission on daily full dose steroids but relapses as soon as steroids started on alternate days or within 14 days of stopping steroids.
- Steroid resistant nephrotic syndrome (SRNS): When failure to attain remission despite 4 weeks of daily full dose of steroids.
Treatment
A. First episode (6+6)
Oral steroid
⇓
2 mg/kg daily × 6 week
↓
1.5 mg/kg alternate days × 6 week
↓
Stop
B. Relapse (2+6)
Oral steroid
⇓
2 mg/kg daily × 2 week
↓
1.5 mg/kg alternate days × 4 week
↓
Stop
C. FRNS / SDNS / Any relapse with steroid toxicity
Daily oral steroid
+
Steroid sparing agent
D. SRNS
Drug of choice: Calcineurin inhibitors
↓If fails
Monoclonal antibody
Vaccination
Two vaccines are mandatory in childhood nephrotic syndrome
⇓
Pneumococcal vaccine
Varicella vaccine
- Dosing time: 1st dose 4 week after last dose of steroids
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