Intro To Renal Pathology

Question 1

What is the Normal Function of the Kidneys? (7)

Answer 1

• Convert 1700 L of blood /day into 1L of urine
• Fluid, electrolytes and acid-base balance
• Excretion of nitrogenous wastes
• Erythropoietin synthesis
• Renin synthesis to maintain blood pressure
• Prostaglandin synthesis
• Vit. D activation (Calcium& phosphate levels)

Question 2

what is GFR and what are the criteria for calculating it?

Answer 2

the volume of fluid filtered from the kidney (Glomerular capillaries) into Bowman’s space / unit time {ml/min}

• Filtration rate of all FUNCTIONING nephrons

• 1- Has a steady level in blood
• 2- Freely filtered
• 3- Not reabsorbed or secreted by renal tubules

Question 3

what is the issue with using Creatinine Clearance (CrCl) or Serum Creatinine to determine GFR?

Answer 3

• CrCL= UCr/PCr X volume/time - Freely filtered, not reabsorbed, but secreted by tubules
- CrCl overestimates or underestimates GFR up to 15%

• Serum Creatinine - influenced by muscle mass

Question 4

What are the 3 Major Causes of Renal Failure?

Answer 4

• 1-Renal ( primary kidney diseases) - Congenital - Acquired (glomerular / tubulointerstitial)
• 2-Pre-renal (inadequate blood supply) - Heart failure - low cardiac out put • - Low renal perfusion • - Volume depletion • - Sepsis • - Severe bleeding
• 3- Post-renal (bilateral urinary obstruction) • - Tumors, BPH ( prostate)

Question 5

What are the 2 major Classifications of Kidney Disease?

Answer 5

1. Glomerular disorders
   - Heavy proteinuria
   - RBC/RBC casts
   - Oval fat bodies
2. Tubulointerstitial disorders. -Mild proteinuria
   - Functional tubular defects.
   - WBC

Question 6

Urinalysis of NEPHROTIC Glomerular Disease?

Answer 6

• Heavy Proteinuria
• Oval Fat Bodies
• Free Fat Droplets
• Few Cellular Elements
• Fatty Casts

Question 7

Urinalysis of NEPHRITIC Glomerular Disease?

Answer 7

• Red Cells
• Red Cell Casts/ Granular Cast
• Variable Proteinuria
• WBC

Question 8

Immune Mechanisms- Antibody Mediated Glomerular Disease?

Answer 8

• In situ Immune Complex (Ag-Ab) formation
  • 1- Fixed antigens ( intrinsic)/ anti GBM nephritis)
  • 2- Planted antigens (exogenous/ endogenous)
• Circulating Immune Complex
  • 1- Endogenous antigens ( DNA) • 2- Exogenous antigens ( infectious protein)
• Cytotoxic antibodies
  • 1- Direct cell injury
  • 2- Without immune complex deposits