Understanding Acute Kidney Injury (AKI)

Apr 16, 2025

Lecture on Acute Kidney Injury (AKI)

Introduction

  • Discussion on Acute Kidney Injury (AKI):
    • Definition: Reduction of renal function following an insult to the kidney.
    • Measured through Glomerular Filtration Rate (GFR).
    • In AKI, there's a reduction in GFR.
    • Consequences:
      • Less blood filtered by the kidneys.
      • Rise in serum creatinine.
      • Reduced urine output.

Creatinine and Kidney Function

  • Creatinine:
    • Byproduct of muscle metabolism.
    • Normally constant serum levels due to balance between muscle production and kidney removal.
    • In AKI, kidneys cannot remove creatinine efficiently, causing serum levels to rise.

Diagnosis of AKI

  • NICE Guidelines:
    • Serum creatinine rise > 26 micromoles/L within 48 hours.
    • Serum creatinine rise > 50% from baseline within 7 days.
    • Urine output < 0.5 mL/kg/hour for more than 6 hours.

Risk Factors

  • Advanced age.
  • Underlying kidney diseases (e.g., chronic kidney disease, polycystic kidney disease).
  • Diabetes.
  • Ongoing illness or recent surgery.
  • Nephrotoxic medications (e.g., NSAIDs, ACE inhibitors).

Causes of AKI

1. Pre-Renal Causes

  • Decreased blood flow to kidneys.
  • Examples:
    • Hypovolemia (due to blood loss, dehydration, vomiting, diarrhea).
    • Low blood pressure.
    • Heart failure.
    • Renal artery stenosis.

2. Intra-Renal Causes

  • Direct damage to the kidney:
    • Can affect glomerulus, tubules, or interstitium.
    • Acute tubular necrosis.
    • Glomerulonephritis.
    • Nephrotoxic compounds (e.g., NSAIDs, ACE inhibitors, iodinated contrast).

3. Post-Renal Causes

  • Pathology downstream from the kidneys:
    • Blockages leading to back pressure.
    • Examples: Benign prostate hyperplasia, prostate cancer, kidney stones, blocked catheter.

Treatment Options

Management of AKI

  1. Pre-Renal AKI:

    • Focus on fluid resuscitation to address volume depletion.
    • Increase blood flow to kidneys.

  2. Intra-Renal AKI:

    • Dependent on underlying pathology.
    • Corticosteroids for inflammatory conditions like glomerulonephritis.
    • Removal of nephrotoxic medication for toxin-induced AKI.

  3. Post-Renal AKI:

    • Bypassing the obstruction using:
      • Urinary catheter.
      • Nephrostomy (artificial opening to bypass bladder).

Conclusion

  • Encourage further study with additional video resources on kidney function.