Diabetic Nephropathy

1. Know the glomerular lesions in DM. Which one is the most characteristic of diabetic nephropathy?

   Nodular intercapillary glomerulosclerosis

• Most characteristic, but not diagnostic (amyloidosis)

• Acellular

• Located in mesangial/intercapillary regions of glomerular tufts

• Laminated appearance and are eosinophilic on H&E stain

• PAS+ and argyrophillic

• Almost always seen with diffuse intercapillary glomerulosclerosis

• Diffuse intercapillary glomerulosclerosis

  • Expansion of mesangial matrix

  • PAS+ and argyrophillic

  • Diffuse and global

  • Wrinkling and thickening of BM can be seen

• Capsular drop lesion

  • Homogenous, waxy eosinophillic mass

  • Appears to be located between BM and overlying parietal epithelium, but lesion is IN Bowman’s capsule

• Fibrin cap lesion

  • Not pathognomonic (FSG, reflux nephropathy, GN, artiosclerosis)

  • Eosinophillic, waxy structure located w/in lumen of one or more capillary loops

  • Red on Trichrome stain

  
  

2. Know the characteristic vascular lesion in diabetic nephropathy

   • Subintimal hyaline change affecting both afferent and efferent arterioles

   
   

3. Know the clinical presentation of diabetic nephropathy

   • Preclinical - microalbuminuria

   • Proteinuria (Nephrotic range in 10-15%)

   • Hematuria

   • Uremia

   
   

4. Know the definition of microalbuminuria

   • Abnormal, but subclinical albuminuria

   • 20 mcg/min, but < 200 mcg/min

   
   

5. Know the mechanism of thickening of the glomerular basement membrane and alteration of glomerular filtration barrier

• Increased collagen IV

• Increased laminin

• Decreased proteoglycans ® less negative charged ® increased permeability to cations

• Increased glomerular capillary pressure also increases permeability

6. Know the hemodynamic change in diabetic nephropathy and its mechanisms

• Larger glomeruli and attendant microvasculature could reduce vascular resistance and increase the surface area for filtration

• Some hormonal aspects (elevated glucagons/growth hormone levels) could cause relaxation of renal vasculature

• Enhanced renal production of prostaglandin occurs

• ECF volume expansion is common in DM

• Atrial peptides contribute to renal vasodilation/hyperfiltration

• Elevated kinin

• Increased dietary protein intake may influence
  

Category: Pathology Notes