Lecture Notes: Nephrotic Syndrome

Overview

• Nephrotic syndrome is a feature of several kidney diseases, not a disease itself
• Key characteristics:
  • Marked proteinuria (> 3.5 grams/day)
  • Hypoalbuminemia
  • General edema
  • Hyperlipidemia

Kidney Structure and Function

• Normal kidney has 1-2 million nephrons
• Glomerular structure includes:
  • Fenestrated endothelium
  • Glomerular basement membrane
  • Protozoites
• Nephron barriers:
  • Size barrier
  • Negative charge barrier
• Glomerulus permits small molecules (e.g., sodium, water) but not large or negatively charged molecules (e.g., proteins)

Pathophysiology of Nephrotic Syndrome

• Damage to glomerulus increases permeability
• Plasma proteins leak into urine (proteinuria > 3.5 grams/day)

Types of Nephrotic Syndrome

• Primary Nephrotic Syndrome: Specific to kidneys
  • Minimal change nephropathy (common in children)
  • Focal glomerulosclerosis
  • Membranous nephropathy
  • Hereditary nephropathies
• Secondary Nephrotic Syndrome: Manifestation of systemic illnesses
  • Diabetes mellitus (diabetic nephropathy)
  • Lupus erythematosus
  • Viral infections (hepatitis B, C, HIV)
  • Amyloidosis, paraproteinemias
  • Preeclampsia
  • Alloantibodies from enzyme replacement therapy

Pathophysiological Effects

• Loss of albumin causes:
  • Hypoalbuminemia
  • Lowered plasma oncotic pressure
  • Hypovolemia
  • Activation of renin-angiotensin-aldosterone system → sodium reabsorption
  • Generalized edema (anasarca)
• Loss of immunoglobulins decreases immunity
• Loss of thyroxine-binding proteins leads to impaired iron transport
• Hypercoagulatability due to loss of antithrombin III and increased fibrinogen
• Hyperlipidemia due to increased hepatic synthesis

Differential Diagnosis

• Acute glomerulonephritis
• Acute and chronic renal failure
• Kwashiorkor
• Allergic reactions
• Congestive cardiac failure
• Liver disease with hypoalbuminemia
• Protein-losing enteropathies

Diagnostic Investigations

• Urinalysis: hematuria, proteinuria
• Complement C3 levels
• Urinary protein measurement
• Serum albumin levels
• Serologic studies for infections and immune abnormalities
• Renal ultrasonography and biopsy

Management

• Dietary Management:
  • Normal protein diet considering nutritional status
  • Low salt intake
• Medication:
  • Corticosteroids (e.g., prednisone)
  • Immunosuppressants (e.g., cyclophosphamide, cyclosporine)
  • Diuretics (e.g., furosemide, spironolactone)
  • ACE inhibitors (e.g., captopril, enalapril)
  • Angiotensin II receptor blockers (e.g., losartan)
• Complication Management:
  • Hypertension treatment (short-term nifedipine, hydralazine)
  • Prevent thrombosis through mobilization
  • Infection management with prophylactic antibiotics (e.g., penicillin)
• Albumin infusion may be used to manage hypovolemia

Conclusion

• Understanding nephrotic syndrome involves recognizing its role in kidney pathology and systemic implications
• Management includes dietary adjustments, pharmacological intervention, and addressing complications

---

Consider subscribing to the channel for more tutorials.