Your thyroid gland controls the metabolism of your body. To stimulate your thyroid, your pituitary gland releases a hormone known as thyroid-stimulating hormone (TSH). Your thyroid then releases two hormones, T3 and T4. These hormones control your metabolism. In hypothyroidism, your thyroid doesn’t produce enough of these hormones. This is also known as an underactive thyroid. There are three types of hypothyroidism: primary, secondary, and tertiary. In primary hypothyroidism, your thyroid is being stimulated properly. However, it isn’t able to produce enough thyroid hormones for your body to function properly. This means that your thyroid itself is the source of the problem. In secondary hypothyroidism, your pituitary gland isn’t stimulating your thyroid to produce enough hormones. In other words, the problem isn’t with your thyroid. The same is true with tertiary hypothyroidism.
What causes primary hypothyroidism?
The most common cause of primary hypothyroidism is Hashimoto’s disease. This is an autoimmune disease that causes your immune system to mistakenly attack your thyroid. You might also develop primary hypothyroidism for a number of other reasons. If you had hyperthyroidism (or overactive thyroid), your treatment may have left you with hypothyroidism. A common treatment for hyperthyroidism is radioactive iodine. This treatment destroys the thyroid. A less common treatment for hyperthyroidism involves the surgical removal of part or all of the thyroid. Both can result in hypothyroidism.If you had thyroid cancer, your doctor would have surgically removed your thyroid, or part of it, to treat cancer.
What are the symptoms of primary hypothyroidism?
The symptoms of hypothyroidism vary widely from person to person. Symptoms typically develop slowly, and depend on the severity of the disease.
At first, you may notice general symptoms including:
Sensitivity to cold
Because the thyroid hormones control the metabolism of all your cells, you might also gain weight.