Graves’ Disease: Life After Radioactive Iodine Treatment

Graves’ disease (GD) is an autoimmune condition affecting approximately 1 - 1.5%¹ of the population. It results in the overproduction of thyroid hormones, creating a state of hyperthyroidism. 

Hyperthyroidism has many negative effects on the endocrine, nervous, skeletal, metabolic, and neuropsychological systems. 

If you have Graves’ disease, it can severely compromise your quality of life, with permanent damage being a possibility if you don’t seek treatment. 

What are the treatments for Graves’ disease?

Three main treatment options address a hyperactive thyroid: antithyroid drugs (ATDs), radioactive iodine therapy (RAI), and surgical gland removal. 

Treatment methods depend on your circumstances, the extent of your hyperthyroidism, and even the country you live in. Specialists have differing views on the most effective treatment for inducing remission while minimizing the risks.  

Since there is no consensus on the "best" treatment, the American Thyroid Association (ATA) guidelines emphasize discussing all options with people. Doctors should consider their patient’s preferences before choosing a treatment.

Generally, you take ATDs for 12 - 18 months² to generate a stable thyroid state. Remission is more likely if you have mild hyperthyroidism, a small goiter, or a goiter that shrinks during ATD treatment.

RAI may be preferable given its lower cost and complication rates than surgery. However, RAI could worsen eye symptoms, so it might not be the best option for you if you have moderate to severe orbitopathy. 

Surgery may be the treatment of choice if you have a very large, obstructive goiter, an allergy to ATDs, and if you are unable or do not want to receive RAI. 

RAI is an effective treatment for Graves’ disease. It was the most popular treatment in the United States according to a 2011 survey, but the popularity of ATDs is increasing.

An updated analysis³ suggests antithyroid drugs have overtaken radioactive iodine as the first treatment for Graves’ disease.

Radioactive iodine therapy

Radioactive iodine therapy (RAI) involves administering radioactive iodine as sodium iodide (131-I) in liquid or capsule form. This radioactive isotope is the precursor to iodine, and the iodide transporters of thyroid cells readily take it up. 

Once there, the radioactive iodine emits beta-particles (ionizing radiation) and causes local damage to the cells around it. 

The aim is the gradual death of the thyroid cells, which essentially “knocks out” the thyroid gland. Ideally, your thyroid hormone concentrations fall, and you become hypothyroid. 

This result occurs for approximately 80%² of people. Another 10%² become euthyroid (thyroid function normalizes), and the remaining 10%² remain hyperthyroid, which usually means another treatment is necessary.  

There are two methods of deciding on a sodium iodide (131-I) dose:

1. A fixed-dose method.

2. A calculated-dose approach where the dose is proportional to the size and iodine uptake of the thyroid determined by ultrasound.

The fixed-dose method is less costly and simplifies the treatment approach compared to individually calculated doses, which requires a hospital trip to measure 24-hour radioiodine uptake. 

The calculated-dose approach aims to maximize cure and avoid unnecessarily high radiation exposures in people with high radioiodine uptake. It has the additional advantage of avoiding undertreatment when people with large goiters and low uptakes receive a fixed-dose.

Short-term effects of RAI

You should be aware of some immediate to short-term side effects of RAI. 

You may get a sore throat and thyroiditis (inflammation of the thyroid), although this usually only occurs in about 1% of² people. If this happens, you may have a temporary increase in thyroid hormone² production, which your doctor can control with an ATD (thioamide). 

If you have Graves’ orbitopathy (GO), a thyroid eye disease resulting from Graves’ disease, your symptoms may worsen after RAI. 

Scientists think this happens because RAI suppresses the regulation of T cells² involved in the immune system. So, your body can still make the antibodies that produce thyroid hormones to excess. 

If you have risk factors for orbitopathy progression, you will need glucocorticoids (typically prednisolone) to prevent your condition from worsening. However, RAI may still be suitable if you have active mild orbitopathy.

Long-term outcomes of RAI

Hypothyroidism

Radioactive iodine treatment ablates your thyroid enough to cause a stable thyroid hormone state. 

Commonly, people develop hypothyroidism after RAI, though the rate at which this occurs within the first year after treatment depends on the radioiodine dose. The higher the dose, the higher the likelihood of hypothyroidism. 

Hypothyroidism can be a long-term side effect and develop years after treatment.

As hypothyroidism can also be harmful, you’ll need long-term follow-ups to measure your thyroid hormone levels after RAI.

Relapse

As with antithyroid medications, relapse is always a possibility. A relapse would mean you’d see a recurrence of your hyperthyroidism symptoms. 

Fortunately, overwhelming evidence suggests RAI will most likely be successful. In one study, radioactive iodine treatment had a success rate of 92%.⁴ 

Fetal risk

As fetal thyroid tissue is present by 10-12 weeks, scientists recommend a 3-6 month⁵ wait for women to conceive following radioactive iodine therapy. Radioactive iodine is transportable across the placenta, which can damage the fetal thyroid gland, and this can cause hypothyroidism and long-term⁶ damage.  

Your doctor should test you for pregnancy before administering RAI if you're a woman.

Malignancy

A large study⁷ found an increase in some cancer types in people who had radioactive iodine treatment for hyperthyroidism compared with the general population. 

The study followed people for 26 years after two or more treatments. Researchers estimated a 12% increased risk⁷ for death from breast cancer and a 5% increased risk⁷ for death from all cancer types involving organs (prostate, breast, and colon, for example). 

With only one treatment, death from breast cancer was no longer an increased risk. The study showed no association between RAI treatment and increased risk of death from leukemia, non-Hodgkin lymphoma, multiple myeloma, or thyroid cancer. 

Another large-scale study⁸ found no increased risk for cancers following RAI therapy.

The conflicting results of these studies highlight the need for additional research to understand the relationship between radioactive iodine treatment and the development of cancers. 

The lowdown

Hyperthyroidism associated with Graves’ disease can cause several negative symptoms. Radioactive iodine therapy (RAI) is one of the three main treatment options. 

Life after RAI treatment may still involve many doctor visits, as they will need to review your thyroid hormone status regularly. 

Generally, your quality of life should improve after RAI, especially if you are one of the approximately 90%⁴ of people who enter remission with one round of treatment.