Answer to Question #7179 Submitted to "Ask the Experts"

Category: Nuclear Medicine Patient Issues — Therapeutic Nuclear Medicine

The following question was answered by an expert in the appropriate field:

When you receive an iodine-131 therapy dose for remnant thyroid cancer, you are asked to drink lots of fluid to rid yourself of the radioactive material faster through your urine.

If you want to get rid of the iodine quicker, why won't nuclear medicine doctors and endocrinologists give continuing intravenous (IV) fluids to increase urine output and thus lower bladder dose in the first 24 to 48 hours? Won't IV fluids increase the biological half-life?


Drinking lots of fluids yourself works just as well as IVs, but with IVs, you need to be an inpatient. It's also uncomfortable, expensive (being an inpatient), and restricting (ever try to take a shower?), not to mention the problems caused by infiltration and occasional infection.

Carol S. Marcus, PhD, MD
Professor of Radiation Oncology and of Radiological Sciences, UCLA

Answer posted on 11 March 2008. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.