What to Know About Hormone Therapy for Thyroid Cancer
If you’ve had surgery to remove your thyroid gland and/or radioactive iodine therapy, your body may no longer make the thyroid hormones it used to make. You will likely be on thyroid hormone therapy, which is usually given in the form of pills. These pills replace your lost hormones. Thyroid hormones are important because they help the body work properly.
The pituitary gland in your brain controls the thyroid. If the pituitary senses that thyroid levels are low, it will make a hormone called thyroid-stimulating hormone (TSH). This hormone normally stimulates the thyroid gland to make as much of its hormones as the body needs. However, if you have had your thyroid removed due to thyroid cancer, TSH may instead stimulate any thyroid cancer cells that remain, and they may grow faster.
Conversely, if the pituitary senses that thyroid hormone levels are increased, it will not make very much TSH. Some studies have shown that people who had thyroid cancer treatment do better when the amount of TSH in their blood is low. So in thyroid cancer patients, enough hormone pills are given to not only help the body work properly, but also to keep TSH levels low.
Side effects of thyroid hormone therapy
Patients on thyroid hormone therapy need regular blood checks to avoid taking too little hormone (which would result in hypothyroidism) or taking too much hormone (which would result in hyperthyroidism). Signs of hypothyroidism include low energy, fatigue, sleepiness, weight gain, feeling cold all the time, hair loss, and dryness of the skin. Hyperthyroidism may cause nervousness, shaking, weight loss without dieting, diarrhea, rapid heartbeat, and excessive sweating. Over time, it may also lead to thinning of the bones (osteoporosis).