A 65-year-old male with a history of diabetes mellitus and hypertension is scheduled for a contrast-enhanced CT scan. His recent serum creatinine is 2.5 mg/dL. Which of the following is the most appropriate next step regarding the administration of iodinated contrast?

Explanation

A serum creatinine of 2.5 mg/dL indicates significant renal impairment (e.g., eGFR likely < 30 mL/min/1.73m²). In patients with severe renal dysfunction, the risk of contrast-induced nephropathy (CIN) is substantially increased. While pre- and post-hydration (Option D) can mitigate the risk in moderate renal impairment, for severe impairment, withholding contrast and seeking alternative imaging (e.g., non-contrast CT, MRI without gadolinium, or ultrasound) is generally the safest and most appropriate approach. Discontinuing metformin (Option B) is important to prevent lactic acidosis in patients with renal impairment who receive contrast, but it does not address the primary risk of CIN from the contrast itself. Diabetes (Option A) is a risk factor for CIN, not a reason to ignore renal impairment.