Acute Renal Failure Pathophysiology Simplified

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Pathophysiology of Acute Renal Failure
Pathophysiology of Acute Renal Failure

Acute Renal Failure

Acute Renal Failure
Acute Renal Failure
  • Can be classified as prerenal failure, intrarenal failure, or postrenal failure.
  • Can be reversible.
  • Can lead to chronic renal failure.
  • Caused by obstruction, poor circulation, or kidney disease.
  • Interruption in flow can lead to serious failure.

Phases of Acute Renal Failure: Oliguric, Diuretic, Recovery (ODR)

Oliguric Phase

Oliguric Phase of Acute Renal Failure
Oliguric Phase of Acute Renal Failure
  • Oliguria – Decreased urine output of less than 400 ml/day
  • Prerenal oliguria – Decreased blood flow to the kidney
  • Impairment of kidney’s ability to conserve sodium
  • Acute tubular necrosis
  • Increased BUN and creatinine levels and decreased ratio of BUN to creatinine
    – Normal levels 20:1
    – Abnormal levels: 10:1
  • Hypervolemia
  • Edema, weight gain, and elevated blood pressure

how to remember this

Logic –┬áIf the kidney is not assist the body in urinating, the fluid is still inside the body. The patient would gain weight due to the fluid retention, which causes edema. The blood pressure would go up as a result!

Diuretic Phase

Diuretic Phase of ARF
Diuretic Phase of Acute Renal Failure
  • Mild increase in BUN and creatinine levels
  • Hypovolemia and weight loss
  • Decreased levels in potassium, sodium, and water levels
  • Can lead to death if untreated

Recovery Phase

Recovery Phase of ARF
Recovery Phase of Acute Renal Failure
  • Normal BUN levels
  • Normal Creatinine levels
  • Urine output between 1 and 2 L a day

what to look out for

Early signs and symptoms

  • Oliguria
  • Azotemia (Excess urea levels in blood)
  • Anuria (Failure to secrete urine). Usually patients can still urinate so this symptom is rare.

Later signs and symptoms

  • Electrolyte imbalance
  • Metabolic acidosis
  • Disruption of other body systems