Which of the following patients presents the HIGHEST risk for contrast-induced nephropathy (CIN) from iodinated contrast administration?

• A eGFR 55 mL/min/1.73m² with diabetes and on metformin
• B eGFR 65 mL/min/1.73m² with hypertension on ACE inhibitor
• C eGFR 40 mL/min/1.73m² with diabetes and congestive heart failure ✓
• D eGFR 50 mL/min/1.73m² with hypothyroidism

Explanation

Risk for CIN (post-contrast acute kidney injury) is highest when multiple risk factors coexist. The combination of eGFR <45 mL/min/1.73m², diabetes mellitus, and heart failure represents the highest-risk triad — reduced renal perfusion (heart failure), diabetic nephropathy, and pre-existing CKD synergistically increase vulnerability. eGFR <30 is the threshold for greatest concern. Metformin does not cause CIN but should be withheld after contrast in patients with eGFR <45 due to risk of lactic acidosis if AKI occurs. ACE inhibitors and hypothyroidism are modest independent risk factors.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.