The document discusses acute renal failure (ARF), defining it as the loss of renal function over hours to days resulting in the accumulation of nitrogenous waste products in the blood. It classifies the etiologies of ARF into prerenal, intrinsic renal, and postrenal causes. Prerenal ARF is due to decreased effective blood volume leading to renal vasoconstriction, while postrenal ARF results from urinary tract obstruction. Intrinsic renal ARF includes acute tubular necrosis, acute interstitial nephritis, and glomerulonephritis. Clinical evaluation involves assessing for risk factors and distinguishing between the types of ARF to guide management and treatment.

1. Acute Renal Failure Paul M. Palevsky, M.D. Professor of Medicine Chief, Renal Section VA Pittsburgh Healthcare System

3. Relationship Between GFR and Serum Creatinine in ARF 120 40 80 0 GFR (mL/min) 0 7 14 21 28 4 Days 2 0 6 Serum Creatinine (mg/dL)

8. Classification of the Etiologies of Acute Renal Failure Acute Renal Failure Acute Tubular Necrosis Acute Interstitial Nephritis Acute GN Acute Vascular Syndromes Intratubular Obstruction Prerenal ARF Postrenal ARF Intrinsic ARF

9. Physiologic Response to Volume Depletion Na Reabsorption AII AII PG RPF GFR P GC FF Urea Reabsorption

10. Prerenal Acute Renal Failure Na Reabsorption AII AII PG RPF GFR P GC FF Urea Reabsorption

11. Pathogenesis of Prerenal Azotemia Renal Vasoconstriction Decreased GFR Angiotensin II Adrenergic nerves Vasopressin + + + Nitric oxide Prostaglandins - - Volume Depletion Congestive Heart Failure Liver Failure Sepsis

16. Fractional Excretion of Sodium FE Na = Filtered Sodium Excreted Sodium FE Na = P Na x GFR U Na x V FE Na = U Cr / P Cr U Na / P Na

20. Postrenal Acute Renal Failure

21. Postrenal Acute Renal Failure

22. Postrenal Acute Renal Failure

30. Renal Ultrasound - Hydronephrosis

33. Acute Tubular Necrosis

35. Pathophysiology of ATN: Tubular Epithelial Cell Injury and Repair Loss of polarity Normal Epithelium Migration , Dedifferentiation of Viable Cells Differentiation & Reestablishment of polarity Sloughing of viable and dead cells with luminal obstruction Ischemia/ Reperfusion Apoptosis Necrosis Cell death Adhesion molecules Na + /K + -ATPase Proliferation

37. Phases of Ischemic ATN Prerenal Initiation Extension Maintenance Recovery GFR Time

38. Pathophysiology of ATN Ischemia Endothelial Injury Capillary Obstruction & Continued Ischemia Inflammation Tubular Injury Disruption of Cytoskeleton Loss of Cell Polarity Desquamation of Cells Tubular Obstruction & Backleak Apoptosis & Necrosis Activation of Vasoconstrictors Impaired Vasodilation Increased Leukocyte Adhesion

41. Acute Tubular Necrosis: Clinical Presentation

44. Mortality in Acute Tubular Necrosis Chertow et al: Arch Int Med 1995; 155:1505-1511 Number of Failed Non-Respiratory Organ Systems

45. Effect of Contrast Nephropathy on Mortality Levy et al: JAMA 1996; 275:1489-1494

47. Acute Interstitial Nephritis

51. Acute Interstitial Nephritis: Clinical Presentation

52. Acute Interstitial Nephritis: Clinical Presentation

55. Acute Glomerulonephritis

58. Atheroembolic Disease

64. Diagnostic Evaluation of ARF Muddy brown casts; tubular epithelial cells > 2% >40 <10:1 ATN Normal or RBC’s variable >20 variable Vascular RBC’s, RBC casts <1% <40 variable AGN WBC’s WBC casts, RBC’s, eosinophils >1% >20 <20:1 AIN Intrinsic Normal or RBC’s variable >20 >20:1 Postrenal Normal < 1% <20 >20:1 Prerenal Urine Sediment FE Na U Na (mEq/L) BUN:Cr Form of ARF