Radioactive Iodine

Summary

Radioactive iodine is an antithyroid treatment that lowers thyroid levels by specifically destroying thyroid tissue. It’s used to treat hyperthyroidism, including hyperthyroidism that occurs in the autoimmune condition Graves’ Disease. Patients need to social distance when taking radioactive iodine to avoid exposing others,  and pregnant women should never take radioactive iodine, as it’s a known teratogen. Because most or all of the thyroid tissue is destroyed by the radioactivity, patients will develop hypothyroidism and will need to take daily thyroid supplements to maintain thyroid levels within normal levels.

Key Points

• Radioactive Iodine
  • Mechanism
    • Iodine is taken up by the thyroid gland and damages it, lowering the amount of thyroid hormones that are released
    • Given as a single-dose pill capsule
    • Patients taking radioactive iodine should maintain their distance from others
      • Including using separate utensils, bathrooms, towels, etc.
  • Clinical Use
    • Treats Hyperthyroidism
      • Graves Disease (thyrotoxicosis)
      • Is a permanent cure, but it may take up to a month for symptoms of hyperthyroidism to subside
    • In smaller doses may be used for thyroid function studies
    • Thyroid cancer
  • Side Effects and Adverse Reactions
    • Hypothyroidism
      • Cold intolerance, edema, bradycardia, weight gain, depression
      • Patients who undergo radioactive iodine will need to take thyroid supplements for the rest of their life.
    • Teratogenic
    • Metal taste
    • Swollen saliva glands
    • Radiation sickness
      • Hematemesis, epistaxis, intense nausea and vomiting
    • Bone marrow depression