Thyroid Cancer: Hormone Therapy

What is hormone therapy?

Hormone therapy uses pills to give your body the hormones that were made by the thyroid gland before cancer treatment. Thyroid hormones are important because they help the body work properly.

When might hormone therapy be used for thyroid cancer?

If you’ve had surgery to remove your thyroid gland or radioactive iodine therapy, your body will no longer make the thyroid hormones it used to make. Your healthcare provider will likely give you thyroid hormone therapy to replace your hormones. You will need take thyroid hormones for the rest of your life.

The pituitary gland in your brain controls the thyroid. If the pituitary senses that thyroid hormone levels are low, it will make a hormone called thyroid-stimulating hormone (TSH). This hormone normally causes the thyroid gland to make as much of its hormones as the body needs. TSH is also known to encourage the growth of the thyroid gland. It may also possibly encourage the growth of thyroid cancer cells. Taking hormone therapy to keep TSH low after you have had your thyroid removed due to cancer, may help prevent some thyroid cancers from returning.

How is hormone therapy given for thyroid cancer?

Hormone therapy is usually given in the form of pills. A balanced amount of hormone pills helps the body work properly and keeps TSH levels low. 

The most commonly used pill is levothyroxine. You take it at about the same time every day. It needs to be taken on an empty stomach, usually first thing in the morning. You do not need to be in the hospital to get this medicine. You can take it at home.

Blood tests will be done regularly to watch your thyroid hormone and TSH levels and adjust the dose as needed. Different amounts are needed for each person, and the dose needed may change over time.

What are common side effects of thyroid hormone therapy?

People on thyroid hormone therapy need regular blood tests to avoid taking too little hormone, which would cause hypothyroidism. The blood tests can also help keep you from taking too much hormone, which would cause hyperthyroidism.

Signs of too little thyroid hormone, or hypothyroidism, include:

• Low energy

• Tiredness or fatigue

• Weight gain

• Feeling cold all the time

• Hair loss

• Dry skin and hair

Signs of too much thyroid hormone, or hyperthyroidism, include:

• Nervousness

• Shaking

• Weight loss without dieting

• Trouble sleeping

• Diarrhea

• Cramps

• Rapid or irregular heartbeat and chest pain

• Excessive sweating and feeling hot

• Thinning of the bones over time; this is called osteoporosis

Talk with your healthcare provider about the signs you should watch for that may mean it's time to adjust your dose of hormone therapy.

Also talk with your healthcare provider about whether you need to take calcium and/or vitamin D supplements.

Working with your healthcare provider

It's important to know which medicines you're taking. Write your medicines down, and ask your healthcare team how they work and what side effects they might have. Also be sure to talk about herbs, vitamins, and supplements you take. Some of these might interact with your hormone therapy.

Know the dose you are taking. And be sure you know how to take your hormone therapy. Keep track of where and how often you need to have blood tests done to check your thyroid hormone levels.

Talk with your healthcare providers about what signs to look for and when to call your healthcare provider about them. Make sure you know what number to call with questions. Is there a different number for evenings and weekends?