Radioactive Iodine Thyroid Treatment

Excess Radiation

• The thyroid absorbs all the radioactive iodine it can, but there is usually some remaining. At that point, the remainder of the radioactive material is secreted through the urine, usually within three days.
  
  

Duration

• Many patients require only one dose of I-131 in order to inhibit the production of excess thyroid hormone. However, one dose is not always sufficient. Some people require a second or third dose of I-131 to fully impair overproduction of thyroid hormone. Doses are usually spaced at least three to six months apart. After receiving the right amount of radioidine, most people attain maximal relief within six months of the last treatment.
  
  

After Treatment

• Since radioactive iodine therapy destroys thyroid tissue, it can actually cause a worsening of the symptoms of hyperthyroidism for as long as a few weeks following administration of I-131. This happens because the thyroid dumps the remnants of the excess thyroid hormone into the bloodstream. Once that is processed and excreted, most people begin to feel better. During the interim, beta-blocker medications can help with the ill effects.
  
  

Side Effects

• Radioactive iodine typically has few side effects. The most common is a sore throat or tenderness in the thyroid gland, which can be alleviated with an over-the-counter pain medication. Some people have a reaction to the iodine itself, which might cause swelling of the salivary glands. Nausea often occurs following ingestion of the radioiodine, so you should avoid eating or drinking for a few hours before and after the procedure.
  
  

Considerations

• Following administration of radioactive iodine, you'll have to avoid being around small children and those with compromised immune systems for a few days, until the body has excreted the excess radioactive material. If you are pregnant or breastfeeding, you should postpone I-131 therapy until you have given birth or have weaned your child.