Understanding Hashimoto’s and Graves’ Disease
While Hashimoto’s is the leading cause of hypothyroidism and Graves’ is the main cause of hyperthyroidism, they’re almost the same disease. They are very similar.
The genes for thyroid disease are genes of iodine tolerance. Those who don’t tolerate iodine, as well as others, are more prone to develop various versions of autoimmune thyroid disease.
There are also different parts of the thyroid that one might attack. That’s because the thyroid, as one of many glands, is controlled by the pituitary and hypothalamus within the brain.
The cycle plays out like this:
- Your thyroid relaxes and does nothing until it is told to work
- It will then work in proportion to the ‘loudness’ of a signal it receives (TSH)
There is a receptor for TSH that sits outside of the thyroid. Essentially, your pituitary releases some TSH into your bloodstream, it hits the receptor, your thyroid is told to work, and it gets to work at the exact amount that the TSH demands.
In cases of Graves’ disease, the immune system attacks the receptor. Even with no TSH being sent to your receptor, because your pituitary does know that something is wrong, that damage to the receptor keeps your thyroid making hormone because it thinks it’s being told to work.
On the other hand, with Hashimoto’s disease, an enzyme that activates iodine called thyroperoxidase and a protein that stores iodine called thyroglobulin are involved. In cases of Hashimoto’s, both of those things are typically the target of the immune attack.
Hashimoto’s essentially attacks things within your thyroid that make hormones. This causes a deficiency in your thyroid’s ability to make hormones in line with the TSH.
How Often Is Hypothyroidism From Hashimoto’s?
About half of people with hypothyroidism have measurable Hashimotp’s antibodies. But, many people with Hashimoto’s don’t have measurable antibodies. Most estimates would say that about 95-97% of hypothyroidism comes from Hashimoto’s.
When it comes to the other side of the coin, Graves’ disease causes about 80% of hyperthyroidism in adults. Other causes can include:
- Toxic nodular goiter
- Pituitary abnormalities
- Acute short-term thyroiditis
- Other rare conditions
What Is Thyroid Stimulating Immunoglobulin?
This is an example of a thyrotropin (another name for TSH) receptor antibody. These antibodies might block thyrotropin or activate it, so they can make your thyroid completely oblivious to TSH or make it think there is more than what is there.
Most commonly, they cause it to do the second, making your thyroid overactive. This is called TSI, and there is a much higher likelihood of overlap between Graves’ disease and TSI than there is with TSI and Hashimoto’s disease.