Patients on metformin with an eGFR of 30 or more and no acute kidney injury can continue metformin when they receive intravenous iodinated contrast. The risk of lactic acidosis in this group is negligible.
Metformin should be withheld at the time of contrast, and for 48 hours afterwards, in patients with an eGFR below 30 or with acute kidney injury, and restarted once renal function is confirmed stable.
- Continue metformin for contrast CT when eGFR is 30 or more and there is no acute kidney injury.
- Withhold metformin for 48 hours after contrast when eGFR is below 30 or kidney injury is present.
- Recheck renal function before restarting in those patients.
- Avoid delaying a needed contrast scan over metformin alone.
Why it matters
Unnecessary metformin holds and scan delays are still common.
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