“How long does nuclear medicine stay in your body?”
How long does nuclear medicine stay in your body, like iodine for example? Are there any long-term adverse effects from it?
1 Answer
The length of time nuclear medicine agents, or radiotracers, remain in your body depends on the type of agen you received. It can range from a few hours to a few days and factors that determine this are the half life of the radioisotope being administered and the biological effects (is how the body handles it in terms of distribution in various organs and excretion from the body).
For iodine, there are two radiotracers commonly used in nuclear medicine: the I 123 isotope which is used for diagnostic studies and the I 131 isotope which is used primarily for therapeutic purposes (mainly thyroid cancer and hyperactive thyroid diseases). I124 is also an isotope used in diagnostic imaging but only in the research setting. Although both are
isotopes of iodine, they have different half-lives (i.e., the time it takes the substance to decay to half its quantity). I123 has a half-life of 13 hrs whereas I 131 has a half-life of 8 days. Because radioiodine of both forms is primarily excreted by the kidneys, kidney function also determines how quickly the radiotracer clears the body.
As for side effects, the vast majority of nuclear medicine agents do not really have any. Radioiodine, however, in adult patients in larger quantities can cause salivary gland swelling and dry mouth primarily. It can also damage normal thyroid tissue so if it’s being used for other purposes (in pediatric patients for a particular nuclear medicine scan or therapy for neuroblastoma or in patients undergoing a particular nuclear medicine scan to evaluate movement disorders), thyroid blockade is performed. This entails either drinking a solution or taking an agent that blocks the thyroid from taking up the radioiodine.
Hope this helps!
For iodine, there are two radiotracers commonly used in nuclear medicine: the I 123 isotope which is used for diagnostic studies and the I 131 isotope which is used primarily for therapeutic purposes (mainly thyroid cancer and hyperactive thyroid diseases). I124 is also an isotope used in diagnostic imaging but only in the research setting. Although both are
isotopes of iodine, they have different half-lives (i.e., the time it takes the substance to decay to half its quantity). I123 has a half-life of 13 hrs whereas I 131 has a half-life of 8 days. Because radioiodine of both forms is primarily excreted by the kidneys, kidney function also determines how quickly the radiotracer clears the body.
As for side effects, the vast majority of nuclear medicine agents do not really have any. Radioiodine, however, in adult patients in larger quantities can cause salivary gland swelling and dry mouth primarily. It can also damage normal thyroid tissue so if it’s being used for other purposes (in pediatric patients for a particular nuclear medicine scan or therapy for neuroblastoma or in patients undergoing a particular nuclear medicine scan to evaluate movement disorders), thyroid blockade is performed. This entails either drinking a solution or taking an agent that blocks the thyroid from taking up the radioiodine.
Hope this helps!
