What are the common causes of hypothyroidism? Hypothyroidism is a condition in which the thyroid gland produces insufficient thyroid hormone, leading to a slow down in metabolism and a cascade of other health problems.
There are 3 types of hypothyroidism:
- primary – the thyroid itself is dysfunctional
- secondary – the pituitary gland is dysfunctional and doesn’t produce enough thyroid stimulating hormone (TSH) to trigger thyroid hormone production
- tertiary – the hypothalamus is dysfunctional and doesn’t produce enough thyrotropin releasing hormone (TRH) to regulate the activities of the pituitary correctly
Common Causes of Hypothyroidism – Primary Hypothyroidism
Primary hypothyroidism covers a spectrum of thyroid disorders that all have one thing in common – the thyroid doesn’t produce enough thyroid hormone. The common causes are:
- iodine deficiency
- Hashimoto’s disease
- thyroid tumors
- thyroid surgery
- radiation treatment, including radioactive iodine
- some medications
- congenital thyroid agenesis
- genetic defects
- abnormal growths
There is more information about the main causes of primary hypothyroidism in this article.
Interesting Questions about Thyroid:
Hyperthyroidism from any cause can make the upper eyelids pull back, but Graves’ disease often causes one or both eyes to bulge out of their sockets. This condition, known as exophthalmos, can cause loss of eye muscle control, double vision, and (rarely) loss of vision. Most cases require no treatment, but some patients may need to see an eye doctor (ophthalmologist) for specialized treatment. This may include steroids, radiation, or surgery.
If you have thyroid disease, your doctor can discuss which treatment is right for you. The two basic goals for treating thyroid disease are to return thyroid hormone levels to normal and to remove potentially cancerous lumps. Treatments include radioactive iodine, antithyroid drugs, beta-blocking drugs, thyroid hormone pills, and surgery. There are several types of treatment:
- Radioactive iodine is used to shrink a thyroid gland that has become enlarged or is producing too much hormone. It may be used on patients with hyperthyroidism, a goiter, or some cases of cancer.
- Surgery is normally used to remove a cancer and may also be used to remove a large goiter.
- Thyroid hormone pills are a common treatment for hypothyroidism, for patients with a goiter, and for patients who have had thyroid surgery. The pills provide the body with the right amount of thyroid hormone.
- Anithyroid drugs and beta-blocking drugs are used to treat hyperthyroid patients.
Signs and symptoms of Hyperthyroidism may include:
- fast heart rate (100-120 beats per minute or higher)
- slightly elevated blood pressure
- nervousness or irritability
- increased perspiration
- muscle weakness (especially in the shoulders, hips, and thighs)
- trembling hands
- weight loss, in spite of a good appetite
- hair loss
- fingernails partially separated from finger-tips (onycholysis)
- swollen fingertips (achropachy or clubbing)
- retracted (pulled back) upper eyelids
- skin changes
- increased frequency of bowel movements
- goiter (an abnormal swelling in the neck caused by an enlarged thyroid gland)
- in women, decreased menstrual flow and less frequent menstrual flow
- in men, slight swelling of the breasts
- in Graves’ disease: thick or swollen skin over the shin bones (pretibial myxedema); eyes that seem to be popping out of their socket (exophthalmos).
Most of these conditions will return to normal after the hyperthyroidism is treated. Certain others may be treated separately.
Have more questions? Need more answers? Check our Full Thyroid FAQ
Causes of Hypothyroidism – Secondary Hypothyroidism
Most cases of secondary hypothyroidism are caused by pituitary cancers (adenomas) that affect its ability to product thyroid stimulating hormone. Surgery or radiation therapy used to treat these and other upper body cancers can also cause it. Occasionally the pituitary may be affected by excess iron caused by a condition called hemochromotosis or other types of invasive inflammations. Head traumas and Sheehan’s syndrome are also known to be contributing factors.
Causes of Hypothyroidism – Tertiary Hypothyroidism
When hyperthyroidism stems from the hypothalamus it’s usually due to Hypothalamic disease. Hypothalamic disease can result from a number of conditions including malnutrition caused by severe eating disorders (anorexia, bulimia etc), radiation, head traumas, tumors, lesions, genetic disorders or physical injury to the hypothalamus.
If you suspect that you could have hyperthyroidism, you should arrange to speak to your doctor as soon as possible and get tested.