Can radioactive iodine (I-131) cause hypothyroidism?

Updated: Mar 03, 2021
  • Author: Philip R Orlander, MD, FACP; Chief Editor: George T Griffing, MD  more...
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Answer

Use of radioactive iodine (I-131) for treatment of Graves disease generally results in permanent hypothyroidism within 3-6 months after therapy. The frequency of hypothyroidism after I-131 treatment is much lower in patients with toxic nodular goiters and those with autonomously functioning thyroid nodules. Patients treated with radioiodine should be monitored for clinical and biochemical evidence of hypothyroidism.


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