Which iodinated contrast agent parameter BEST predicts the risk of contrast-induced acute kidney injury (CI-AKI)?
- A Iodine concentration in mg/mL only
- B Volume of contrast used regardless of osmolality
- C Osmolality of the contrast medium — high osmolality agents carry higher CI-AKI risk than iso-osmolar agents ✓
- D The presence of ionic vs. non-ionic backbone irrespective of osmolality
Correct answer: C. Osmolality of the contrast medium — high osmolality agents carry higher CI-AKI risk than iso-osmolar agents
Explanation
Osmolality is the major determinant of nephrotoxicity among iodinated contrast media. High-osmolality contrast agents (HOCA, ~1500–2000 mOsm/kg) carry significantly higher risk of CI-AKI than low-osmolality (LOCA, ~600–900 mOsm/kg) or iso-osmolar agents (~290 mOsm/kg, e.g., iodixanol). While volume also matters, osmolality is the primary physicochemical risk factor. Ionic vs. non-ionic distinction largely overlaps with osmolality (modern non-ionic agents are low-osmolality).
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
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