What Is Post-ablative Hypothyroidism?

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Post-ablative hypothyroidism can happen after you have a thyroid ablation to treat certain thyroid diseases. Thyroid ablation is a common, non-surgical medical procedure that decreases the function of some, or all, of the thyroid gland. It can be used to treat hyperthyroidism, Graves’ disease, or thyroid cancer.

Radioactive iodine (RAI) treatment is the most common form of thyroid ablation. The treatment involves taking radioactive iodine (iodine 131) that is absorbed by the thyroid gland, then destroying (ablating) all or part of the gland. This affects the thyroid’s ability to make enough thyroid hormone to support the body and commonly causes low thyroid function (hypothyroidism).

This article explores post-ablative hypothyroidism causes, symptoms, diagnosis, treatment, and prevention.

Woman seeing an endocrinologist and getting a neck exam for a thyroid check.

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Post-ablative Hypothyroidism Causes

The thyroid gland produces and releases thyroid hormones into the bloodstream to help regulate the body’s metabolism. The thyroid's function affects almost all body processes, including the central nervous system, digestion, menstruation, body temperature, development, and heart, bone, and muscle health. 

If all or part of the thyroid gland is destroyed (ablated), it cannot produce sufficient levels of thyroid hormone to support the body’s needs. This leads to an underactive thyroid (hypothyroidism). 

How Common Is Post-ablative Hypothyroidism?

Up to 80% of people who have undergone radioactive iodine treatment for thyroid disease develop post-ablative hypothyroidism within six months.

Common causes of post-ablative hypothyroidism include:

  • History of thyroid disease (e.g., Graves’ disease, hyperthyroidism) 
  • Antithyroid treatment/medications taken prior to ablation
  • History of thyroid cancer
  • Presence of thyroid antibodies 
  • High RAI dose

Post-ablative Hypothyroidism Symptoms

Post-ablative hypothyroidism typically occurs three to six months after radioactive iodine treatment. Common post-ablative hypothyroidism symptoms include:

  • Cold intolerance 
  • Constipation 
  • Dry, coarse skin 
  • Dry, thinning hair
  • Fatigue
  • Infertility 
  • Menstrual problems 
  • Slowed heart rate
  • Weight gain


People who have all of their thyroid glands removed through ablation are immediately diagnosed with hypothyroidism because there is no way for the body to continue producing thyroid hormone on its own.

If you still have part of your thyroid gland, your healthcare provider will order thyroid blood tests to measure the levels of thyroid hormone in your bloodstream starting four to six weeks after treatment.

Thyroid blood tests will be repeated every one to three months for the first year. After that, your thyroid hormone levels will be checked annually. However, let your provider know if you develop hypothyroidism symptoms in between appointments.


Thyroid hormone replacement therapy is the standard treatment for post-ablative hypothyroidism. Synthroid, Levoxyl, Unithroid, or Levothroid (levothyroxine)—a synthetic version of the thyroid hormone thyroxine (T4)—is taken daily to restore and stabilize thyroid hormone levels.

For most people, thyroid hormone replacement is a lifelong treatment. It is very important that you keep taking the medication even if you no longer have hypothyroidism symptoms. 

A small percentage of people with post-ablative hypothyroidism experience a temporary deficiency of thyroid hormone and only need short-term treatment with thyroid hormone replacement therapy. This condition is called “transient hypothyroidism.”

However, this condition almost always eventually progresses to permanent hypothyroidism. 


In most cases, you cannot prevent post-ablative hypothyroidism. An older study from 2002 found that higher radioactive iodine doses were associated with a reduced incidence of early-onset hypothyroidism. Still, the risk of developing late-onset hypothyroidism post-ablation increased by 3% each year after the procedure.

A more recent study in 2016 found that the more risk factors a person has—including the presence of thyroid antibodies, large goiter (enlarged thyroid gland) size, and a history of Graves’ disease—the higher their risk for developing post-ablative hypothyroidism soon after the procedure.


Post-ablative hypothyroidism occurs after thyroid gland ablation when the thyroid gland does not make enough thyroid hormone to meet the body's needs. Radioactive iodine (RAI) treatment is the most common thyroid ablation procedure in the U.S. It treats thyroid diseases like hyperthyroidism, Graves’ disease, or thyroid cancer. 

Symptoms of post-ablation hypothyroidism include fatigue, weight gain, cold intolerance, depression, and dry, coarse skin and hair. Levothyroxine, a synthetic version of the thyroid hormone thyroxine (T4), is highly effective at treating hypothyroidism. Most people need to stay on the treatment for life.

A Word From Verywell

Developing post-ablative hypothyroidism after a thyroid ablation is very common. Talk to your healthcare provider about any hypothyroidism symptoms you develop after a thyroid ablation procedure so you can start treatment if needed.

Frequently Asked Questions

  • What is ablation?

    Thyroid ablation is a medical procedure that involves destroying (ablating) all or part of the thyroid gland. The most common form of thyroid ablation in the U.S. is radioactive iodine treatment (RAI). 

  • What causes post-ablative hypothyroidism?

    Post-ablative hypothyroidism happens because the thyroid gland is not making enough thyroid hormone to support the body’s needs.

    Hypothyroidism occurs immediately if the entire thyroid gland is ablated. People who have part of their thyroid gland remaining may develop hypothyroidism within a year after the ablation.

  • Does hypothyroidism always occur after ablation?

    Hypothyroidism does not always occur after ablation, but it is highly likely. An estimated 80% of people who had a thyroid ablation develop hypothyroidism within a year after the procedure.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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