Why is it essential to monitor kidney function before administering Tc-99m?

• A. To determine the patient's weight
• B. To ascertain the dosage based on kidney size
• C. To ensure the radiopharmaceutical is properly excreted
• D. To assess if the patient is allergic to the radiopharmaceutical

Answer: (C)

Monitoring kidney function before administering Tc-99m is essential primarily to ensure the radiopharmaceutical is properly excreted. Technetium-99m is often used in imaging procedures due to its suitable half-life and gamma emission properties, but its effective clearance from the body is heavily reliant on renal function. If the kidneys are not functioning appropriately, there is a risk of prolonged retention of the radiopharmaceutical, which could lead to higher radiation exposure for the patient and potentially interfere with the imaging results. This aspect is critical not only for patient safety but also for the accuracy of the diagnostic procedure, as adequate excretion is necessary to achieve clear imaging and avoid complications. Therefore, assessing kidney function is a vital step to ensure that the imaging agent does not accumulate in the body beyond intended limits and that it can be eliminated efficiently after the procedure.