Nephrotic Syndrome

Know the urinary findings, blood chemical profile, and clinical presentation of Nephrotic Syndrome

• Proteinuria

• Hypoalbuminemia

• Lipiduria

• Hyperlipidemia

• Edema

Know the filtration barriers in the glomeruli

• Includes endothelial cells, BM, epithelial cells, and slit diaphragms

• Size barrier at level of endothelial cells and GBM restricts filtration of molecules > 42 Å

• Negative electrical charge barrier due to polyanionic sialoprotein coating of endothelial and epithelial cells and presence of heperan sulfate containing GAGs in the lamina rara externa and interna

• Maintenance of RBF and therefore hydrostatic pressure, also influences filtration

Know the mechanism of proteinuria in Nephrotic Syndrome

• Loss of net negative charge on capillary wall (Minimal Change Disease)

• Extensive capillary wall immune deposits (Membranous Nephropathy)

• Disorders of BM biochemistry/structure (diabetes)

Know the most common causes of Nephrotic Syndrome in children and adults

• 33% adults / 10% kids – secondary to systemic disease (diabetes, SLE, amyloidosis)

• 66% adults / 90% kids – idiopathic and a manifestation of Minimal Change Disease, Membranous Nephropathy, or Membrano Proliferative Glomerulo Nephritis

• In patients > 45, may be associated with malignancy

  • Hodgkin’s disease  Minimal Change Disease

  • Breast, lung, GI tumors  Membranous Nephropathy

Know the complications of Nephrotic Syndrome

• Severe protein malnutrition

• Hypercoagulability  thrombus formation  acute renal failure

• ARF (rare) – usually occurs as a consequence of several conditions superimposed on nephrotic glomerular damage

  • Reduced renal perfusion due to low volume  acute tubular necrosis

  • Interstitial renal edema  increased intrarenal pressure  cessation of filtration

  • Drug-induced allergic interstitial nephritis

  • NSAIDs  inhibition of prostaglandin synthesis

  • Bilateral acute renal vein thrombosis (very rare)

• Reduced levels of IgG  susceptibility to infection

• Proximal tubular dysfunction  Fanconi’s Syndrome (anuria, glycosuria, phosphaturia, proximal tubular acidosis)

• Deficiencies of trace metals

• Vitamin D deficiency  osteomalacia and secondary hyperPTH

Category: Pathology Notes