Iodine-131 is used to treat hyperthyroidism and thyroid cancer. For diagnostic purposes, it is used in a specialized imaging procedure known as a thyroid scan. During this type of procedure, a device uses small amounts of radiation to produce images of the thyroid gland. These images help the doctor assess the degree of functionality of the gland.


What is Iodine-131?

Iodine-131 is a radioactive isotope. It is taken orally and it is absorbed into the intestine. When it enters the bloodstream, it is absorbed by the thyroid gland, which goes on to exert its effect. The thyroid gland needs iodine, which is a mineral that is essential for the synthesis of thyroid hormones T3 and T4. The radioactivity of this isotope ends up producing irreversible damage to the thyroid cells, thus improving the framework of hyperthyroidism. It is important to know that the therapeutic effect of iodine-131 is not immediate and in order to be fully eliminated, it may take a few months. 


How should Iodine-131 be taken?

Iodine 131 is taken orally.


Side effects associated with Iodine-131

Iodine-131 is used much more for therapeutic purposes in comparison to diagnostic purposes. Possible side effects of this drug include the following:


  • Gastro-intestinal disorders
  • Sore throat
  • Inflammation of the salivary glands
  • Changes in taste


Keep in mind that in the initial phase of treatment, transient hyperthyroidism and physiological deterioration of the thyroid cells due to inflammation produced by the drug, may occur.


Contraindications and warnings associated with the use of Iodine-131

Iodine-131 is contraindicated in women who are pregnant or lactating due to its toxic effects. Once treatment is set in motion, it is best to wait at least six months before attempting another pregnancy.   Treatment with iodine-131 is also contraindicated in case of excessive intake of thyroid hormone-based drugs and in the presence of thyroiditis.