Understanding Nephrotic Syndrome Management

Mar 5, 2025

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Nephrotic Syndrome Lecture Notes

Overview

  • Nephrotic syndrome involves damage to the kidneys resulting in significant protein loss in the urine (proteinuria).
  • Distinguished from nephritic syndrome by the amount of proteinuria and absence of hematuria.
  • Defined by proteinuria (>3.5 g/day), hypoalbuminemia (low blood albumin levels), and edema.

Kidney Structure & Function

  • Nephron: Functional unit of the kidney.
  • Glomerulus Filtration Barrier: Composed of fenestrated endothelium, glomerular basement membrane, and podocyte foot processes with a net negative charge.
  • Albumin: Normally repelled by the negative charge; damage increases permeability, causing albumin to be lost in urine.

Pathophysiology

  • Hypoalbuminemia: Causes peripheral edema, fluid overload, and weight gain.
  • Edema Mechanism:
    • Reduced oncotic pressure causes fluid to leak into tissues.
    • Triggers renin-angiotensin-aldosterone system (underfill hypothesis).
    • Overfill hypothesis: Defective sodium excretion leads to fluid retention.
  • Hypercoagulability: Loss of antithrombin 3 increases thrombotic risk.
  • Hyperlipidemia: Liver increases lipoprotein production due to protein deficiency.
  • Infections: Increased due to low immunoglobulin levels and edema.
  • Frothy Urine: Indicates high protein content.
  • Additional Symptoms: Loss of appetite, lethargy, and tiredness.

Causes

  • Primary Causes: Direct kidney pathology, often idiopathic.
  • Secondary Causes: Other conditions affecting kidneys.
  • Histological Patterns:
    • Minimal Change Disease: Common in children, visible only under electron microscope.
    • Focal Segmental Glomerulosclerosis: Associated with HIV, obesity, and certain drugs.
    • Membranous Nephropathy: Thickening of the basement membrane with immune deposits.
    • Diabetic Nephropathy: Progressive from microalbuminuria.
    • Amyloidosis: Protein deposition in tissues.

Epidemiology

  • More common in adults (~40 years) than children.
  • Males more affected than females in children, equalizes after adolescence.

Diagnosis

  • Proteinuria Confirmation:
    • Urine dipstick and urinalysis (24-hour collection).
    • Protein-to-creatinine ratio on spot urine sample.
  • Blood Tests: Assess albumin, lipids, and renal function.
  • Further Tests: Immune markers, imaging, and kidney biopsy (mostly in adults).

Treatment

  • Primary Goals: Symptom reduction and underlying cause treatment.
  • Steroids: Prednisone and prednisolone are the mainstays.
  • Steroid Resistance: 10-20% of cases require additional immunosuppressive therapy like cyclophosphamide.
  • Managing Fluid Overload: Diuretics such as furosemide.
  • Diet Modification: Protein intake limited to 1 g/kg/day, restrict salt and fluid.
  • Hyperlipidemia: Treated with statins.
  • Thromboembolism Risk Reduction: Prophylactic heparin, especially in prolonged steroid-resistant cases.

These notes should serve as a concise review of nephrotic syndrome, covering its key aspects, pathophysiology, diagnostic criteria, and management strategies.

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