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Contrast-Induced Nephropathy

Contrast-induced nephropathy (CIN) is an acute decline in renal function after iodinated contrast exposure, especially in high-risk patients with pre-existing kidney disease or diabetes.

Definition:

  • Acute kidney injury (↑ serum creatinine ≥ 0.5 mg/dL or ≥ 25% from baseline) within 48–72 hours of contrast administration

  • Usually reversible within 7–10 days

  • Not due to other identifiable causes

Pathophysiology:

  • Renal vasoconstriction and medullary hypoxia

  • Direct tubular epithelial cell toxicity

Risk Factors:

  • Chronic kidney disease (eGFR < 60 mL/min/1.73m²)

  • Diabetes mellitus

  • Dehydration

  • Use of nephrotoxic drugs (NSAIDs, aminoglycosides)

  • High contrast volume

  • Advanced age

  • Recent contrast exposure

Prevention:

  • IV hydration with isotonic saline (e.g., 0.9% NaCl) pre- and post-procedure

  • Use of low- or iso-osmolar contrast agents

  • Minimise contrast volume

  • Withhold nephrotoxic medications temporarily (e.g., NSAIDs, metformin)

  • Consider N-acetylcysteine (controversial benefit)

Management:

  • Supportive care

  • Monitor renal function post-contrast

  • Dialysis is rarely needed unless other causes of AKI exist

Orthopaedic Relevance:

  • Consider when ordering contrast-enhanced CT, angiography or preoperative vascular studies in high-risk patients

  • Always document renal function status before contrast studies

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