Which pre-procedure step helps determine the safety of using contrast dye during cardiac catheterization?

• A. Measuring blood cholesterol
• B. Assessing lung capacity
• C. Evaluating thyroid function
• D. Checking kidney function

Answer: (D)

Before giving iodinated contrast, evaluating kidney function is crucial because the dye is cleared by the kidneys and can cause contrast-induced nephropathy in susceptible patients. The key pre-procedure step is checking kidney function with serum creatinine and estimating the glomerular filtration rate (eGFR). If kidney function is reduced, risk is higher, so clinicians may limit contrast volume, use a safer (lower- or iso-osmolar) contrast agent, ensure adequate hydration, or consider alternative imaging strategies. Measuring cholesterol, lung capacity, or thyroid function does not directly indicate the kidneys’ ability to handle the contrast, so they are not used to determine safety for this procedure.