Drug-Induced Kidney Injury

DIKI: Intro & Mechanisms - Kidney Under Siege

• Drug-Induced Kidney Injury (DIKI): Adverse renal events from drugs/diagnostic agents, impairing kidney function. Often reversible if detected early.
• Primary Mechanisms:
  • Altered Hemodynamics: NSAIDs, ACEi affect renal blood flow/filtration.
  • Acute Tubular Necrosis (ATN): Direct tubular cell toxicity (aminoglycosides, contrast).
  • Acute Interstitial Nephritis (AIN): Allergic inflammation (penicillins, PPIs).
  • Crystal Nephropathy: Drug precipitation in tubules (sulfonamides, acyclovir).
  • Osmotic Nephrosis: High osmolar agents, tubular swelling (mannitol).

⭐ Acute Tubular Necrosis (ATN) is the most common form of drug-induced kidney injury.

DIKI: Culprit Drugs - Nephrotox Hit Parade

DIKI: Clinical & Diagnosis - Detective Work DIKI

• History is Key: Meticulous drug history (timing, dose, recent changes).
• Clinical Clues: Often asymptomatic. May see ↑SCr, oliguria.
  • AIN: Fever, rash, arthralgia, eosinophilia.
  • ATN: Muddy brown casts.
• Investigations:
  • Urinalysis: Proteinuria, hematuria, specific casts.
  • Urine Eosinophils: For suspected AIN.
  • Serum Creatinine: Monitor trends (e.g., rise of ≥0.3 mg/dL or ≥50% from baseline).
  • Renal Ultrasound: Rule out obstruction.
  • Kidney Biopsy: Gold standard if diagnosis unclear.

⭐ Eosinophiluria is a classic, though not pathognomonic (found in ~70% cases), finding in drug-induced Acute Interstitial Nephritis (AIN).

DIKI: Management & Prevention - Kidney Guardian Guide

• General Management:
  • Discontinue offending drug(s) immediately.
  • Optimize hemodynamics: ensure adequate hydration (IV fluids if needed).
  • Correct electrolyte imbalances (e.g., hyperkalemia).
  • Adjust dosages of other renally excreted drugs.
  • Renal replacement therapy (RRT) if severe (e.g., uremic symptoms, refractory hyperkalemia/acidosis).
• Prevention Strategies:
  • Identify high-risk patients (e.g., pre-existing CKD, elderly, diabetes, volume depletion).
  • Avoid nephrotoxic drug combinations.
  • Ensure adequate hydration, especially before/after contrast media or nephrotoxic drugs.
  • Monitor renal function (serum creatinine, eGFR, urine output) regularly.
  • Use a_lternative non-nephrotoxic agents when possible.

⭐ For preventing Contrast-Induced Nephropathy (CIN), isotonic saline hydration is key; N-acetylcysteine use is controversial but sometimes considered.

High‑Yield Points - ⚡ Biggest Takeaways

• Acute Tubular Necrosis (ATN) is the most common DIKI, often from aminoglycosides, contrast media, and cisplatin.
• Acute Interstitial Nephritis (AIN) is an allergic reaction (e.g., penicillins, NSAIDs, PPIs), presenting with eosinophilia, rash, and fever.
• Prerenal AKI can be induced by ACE inhibitors/ARBs or NSAIDs (by ↓ prostaglandin synthesis).
• Chronic Interstitial Nephritis is linked to long-term lithium or analgesic abuse (e.g., phenacetin).
• Crystalline Nephropathy may be caused by drugs like acyclovir, sulfonamides, and methotrexate.
• Rhabdomyolysis (e.g., from statins, especially with fibrates) can also precipitate AKI by myoglobinuria.
• Key diagnostic clues include temporal drug exposure, urinalysis findings (muddy brown casts in ATN, WBC casts/eosinophiluria in AIN), and renal function tests (↑ serum creatinine, ↑ BUN).