Immunotherapy induced hypothyroidism

What is the thyroid?

The thyroid is a small, butterfly-shaped gland in the neck, just in front of the windpipe. One of its main functions is to produce hormones that help regulate the body's metabolism (the process that turns food into energy).

Many of the body's functions slow down when the thyroid does not produce enough of these hormones.

What is immunotherapy induced hypothyroidism?

Immunotherapy is a treatment for cancer that helps the immune system recognise, target, and eliminate cancer cells, wherever they are in the body. Many cancers employ methods to hide themselves from the body’s immune cells. Immunotherapy blocks these evasion strategies, so the body’s immune system can recognise and kill the cancer cells.

In some people, immunotherapy can cause your immune system to attack normal tissues within your body, causing inflammation. When the thyroid is affected or inflamed it no longer functions properly.

Symptoms of hypothyroidism

It is common for hypothyroidism to be picked up in your blood tests without you feeling any symptoms. Some common symptoms of an underactive thyroid include:

• Tiredness.
• Weight gain.
• Feeling depressed.
• Being sensitive to the cold.
• Dry skin and hair.
• Muscle aches.

Treatment for hypothyroidism

Hypothyroidism can be treated by taking a drug called Levothyroxine which replaces your body’s hormones that are no longer being produced by your thyroid gland. This will be prescribed by your oncology team initially and then by your GP.

You will need to take this tablet every day. Levothyroxine is generally well tolerated and is very safe to take. It is important to take it in the morning around 30 to 60 minutes before having breakfast, drinks containing caffeine, or other medication.

This medication will likely be lifelong, and you will need blood tests on a regular basis to monitor your thyroid function tests.