Radioisotope treatment of hyperthyroidism

"With today's treatment guidelines, hyperthyroidism is an easily controllable and curable disease".


Radioisotope treatment for hyperthyroidism is a type of metabolic radiotherapy that consists of the therapeutic administration of radioiodine (dose of 5 to 15 mCi) to partially destroy the hyperfunctioning thyroid tissue.

It is used for the treatment of different causes of hyperthyroidism (usually Graves-Basedow Disease) after failure of pharmacological therapy.

Radioiodine treatment is performed in the Nuclear Medicine Service. Radioiodine is administered orally in a single dose after the patient has been fasting for the previous six to eight hours.

The low dose of radioiodine administered in this treatment does not require strict hospitalization of the patient, although it is advisable during the 24 hours following treatment.

At the doses used in this type of treatment, there are no appreciable risks secondary to irradiation. It has not been demonstrated that there is a measurable increase in the incidence of tumours in patients treated with radioiodine at hyperthyroidism treatment doses.

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When is radioactive iodine treatment indicated for hyperthyroidism?

If the goiter is small in size or there is a high surgical risk, a dose of radioactive iodine can be administered orally and will take effect in 1-2 months.

This option has the disadvantage of frequently causing hypothyroidism and of favoring more frequently than surgery the deterioration of the ocular alterations in Graves-Basedow disease.

Both surgery and radioactive iodine can cause hypothyroidism, which must be treated for life with thyroxine tablets. The dose adjustment is simple and in a state of compensation the condition does not imply any limitation.

Most frequent indications for this treatment:

Do you have any of these diseases?

Radioisotope treatment may be necessary

How is radioactive iodine treatment performed?

Radioiodine is administered orally in a single dose after the patient has been fasting for the previous six to eight hours.

In the event that the patient is admitted, this will be 24 to 48 hours. The effect of the treatment may not be appreciable until after one or two months, so in some cases it is necessary to resume antithyroid treatment.

In the days following the administration of the treatment you may notice some discomfort in the neck expressive of the inflammation by irradiation of the thyroid gland. Sometimes an exacerbation of the symptoms of thyroid hyperfunction can be observed.

However, in the event that both side effects appear they are easily treatable.

The most common late complication is permanent thyroid hypofunction (10-15% of all cases). This complication is not easily predictable and would force treatment with thyroid hormone supplements, whose tolerance is much higher than that of antithyroid drugs. However, thyroid hypofunction or hypothyroidism is the natural evolution of most causes of hyperthyroidism.

The administration of treatment with radioiodine is contraindicated in pregnant patients because of the risk that radiation will affect the development of the child before birth.

Because the body retains the radioiodine during the six months following its administration, pregnancy should be avoided during this period. Once this time has elapsed, there is no longer any appreciable risk.

The treatment must be indicated by a specialist, after having evaluated the different therapeutic alternatives for your hyperthyroid disease. In the event that the patient is under antithyroid treatment, it is advisable to suspend it three or four days before the administration of the radioiodine.

Likewise, it will suppress the intake of iodized salt and foods with high iodine content. It is also recommended to restrict those drugs that interfere with the incorporation of radioiodine (topical iodine tinctures, amiodarone, anxiolytics, antidepressants, etc.). However, your physician should advise you in this regard.

Where do we do it?


The Thyroid Pathology Area
of the Clínica Universidad de Navarra

The Thyroid Pathology Area is made up of a multidisciplinary team of specialists who work together to offer patients with thyroid problems an accurate diagnosis.

After the diagnosis, the patient is indicated the most appropriate treatment for his or her case and a continuous follow-up is carried out to achieve the desired objectives.

The Clinic is a pioneer in the implementation of medical techniques in Spain and worldwide, and is an international reference in highly specialized procedures.

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Why at the Clinica?

  • Prestigious professionals who are a national reference.
  • In 24-48 hours we make the diagnosis and we can start the most appropriate treatment for each patient.

Our team of professionals

Thyroid specialists with experience in radioactive iodine treatment