Featuring Dr. Richard Bebb, MD, ABIM, FRCPC, Endocrinologist

Duration: 3 minutes, 34 seconds

There are a number of causes of an overactive thyroid or hyperthyroidism.

One of the most common causes is Graves' disease. When you say "graves" to people, they sort of get worried that I have a bad disease. It's actually named after someone called Graves.

In other countries, it's called Basedow's disease or Perry's disease. It's all the same disease. Graves' disease is the terminology used in the United States and Canada. It is an autoimmune disease.

In this situation, the autoimmunity, your immune system attacking your thyroid actually ends up producing an antibody, which causes the thyroid to be stuck on 10 out of 10. It's stuck on full. Again, the accelerator's stuck on the ground.

That antibody persists in your serum, in your blood. With this is a tendency to be a hereditary issue. If you have thyroid disease in the family, whether that's an overactive thyroid or an underactive thyroid, you have an increased risk of having Graves' disease.

Other causes of an overactive thyroid include what we call inflammatory thyroiditis. It's an inflammation of the thyroid and that can occur in three different forms. There's a form that occurs right after pregnancy, usually in the first three to six months of having delivered. There's a form that occurs with no pain at all, it's called silent thyroiditis, silent because it's non painful and, then, something called subacute thyroiditis, which can be incredibly painful.

These inflammatory thyroiditis entities have a self-limited time frame, where they have inflammation in the thyroid, overproduction of thyroid hormone, for three, four, maybe five months.

Following that, there's often resolution, where the thyroid will return to normal. Occasionally, the inflammation is so severe that an underactive thyroid will result, requiring replacement of the thyroid hormone.

The differentiation between Graves' disease and the inflammatory thyroiditis is our most common thing we have to deal with in the office. Your healthcare practitioner can help order the appropriate tests to make that distinction.

Other causes of hyperthyroidism can include toxic nodules, where a little part of the thyroid decides to make hormone on its own, multinodular thyroids, or drug induced. There are certain drugs, like amiodarone or interferon, that have as part of their drug side effect profile making your thyroid become overactive.

The take home point is there are many causes of an overactive thyroid. Some of them will go away on their own with some encouragement. Some won't, like Graves' disease, and they require some definitive therapy to bring you back to normal physiology with normal thyroid levels.

If you think you have a thyroid condition, your primary care practitioner may be able to help you, or perhaps in conjunction with consultation with an endocrinologist.

Presenter: Dr. Richard Bebb, Endocrinologist, Victoria, BC

Local Practitioners: Endocrinologist