Radiologic Technologist Practice Exam

Which medication should be withheld on the day of an iodinated contrast study for patients with diabetes?

1. Furosemide (Lasix)

2. Insulin

3. Metformin

4. Diphenhydramine hydrochloride (Benadryl)

The correct answer is: Metformin

Withholding metformin on the day of an iodinated contrast study is primarily due to the risk of lactic acidosis, a rare but serious condition that can occur in patients with renal impairment, particularly after receiving iodinated contrast media. Metformin is primarily eliminated by the kidneys, and when contrast material is used, there is a possibility of transient kidney dysfunction. If the kidneys do not function adequately to clear the metformin due to this impairment, it can lead to the accumulation of the drug in the body. In diabetic patients who are undergoing an iodinated contrast study, it's crucial to assess kidney function before the procedure. If the patient's renal function is compromised, the use of metformin may need to be avoided not just on the day of the procedure, but for at least 48 hours afterward, until it is confirmed that renal function has returned to baseline levels. This precaution helps to mitigate the risk of lactic acidosis and maintains patient safety throughout the imaging process.