Iodinated contrast: screening before and monitoring after
Three questions before any examination with iodinated contrast: what is the kidney function, what does the person take, and has there been a previous reaction. Kidney function: a recent creatinine and an estimated glomerular filtration rate. The lower the filtration rate, the higher the risk of contrast-associated kidney injury. Hydration before and after is the measure with the best support. Medications: metformin is usually held around the examination when kidney function is reduced, and restarted only after the creatinine has been rechecked. Non-steroidal anti-inflammatories and diuretics add to the renal risk and are reviewed with the prescriber. Previous reaction: a documented reaction to contrast changes the plan and may require premedication. A shellfish allergy is not a contraindication; that association is a persistent myth. What matters is a previous reaction to the contrast itself. After: encourage fluids, monitor urine output, and recheck the creatinine at the interval prescribed. Report a fall in urine output. Watch for a delayed reaction, which can appear hours later as a rash or itching.