Why should metformin be withheld around radiologic procedures with iodinated contrast and when can it be resumed?

• A. Risk of lactic acidosis with contrast-induced nephropathy; hold metformin before imaging and reassess renal function before resuming (often 48 hours after).
• B. Risk of hyperglycemia with contrast; resume immediately after.
• C. Metformin has no interaction with contrast; resume after.
• D. Risk of hypoglycemia with contrast; resume after 1 week.

Answer: (A)