Secondary hyperthyroidism occurs when the thyroid gland produces too much thyroid hormone. It can often be caused by a benign tumor of the pituitary gland. The primary treatment option is surgery.

Secondary hyperthyroidism is a rare condition that develops from a problem with your pituitary gland, a small gland in your brain that tells your thyroid to make thyroid hormone. In this case, the pituitary gland tells the thyroid to make a lot of thyroid hormone.

It is often caused by a tumor affecting the pituitary gland at the base of your brain.

Learn more about what causes secondary hyperthyroidism, symptoms to know about, and how it is diagnosed and treated.

Thyroid hormones stimulate your metabolism and control how quickly your body uses energy. Having too much thyroid hormone circulating in your body can cause several processes to “speed up”.

The symptoms of hyperthyroidism include:

Secondary hyperthyroidism is caused by a tumor affecting the pituitary gland at the base of your brain. Due to this, people with secondary hyperthyroidism may also experience:

Secondary hyperthyroidism is often caused by a pituitary adenoma, a benign tumor that affects the pituitary gland.

The pituitary gland is found at the base of your brain just above your nasal passages. It makes several hormones that work to direct different processes in your body.

One of these hormones is thyroid-stimulating hormone (TSH), which tells your thyroid gland to make more thyroid hormone.

Some pituitary adenomas can make excess hormones, including TSH, which boosts thyroid hormone production, resulting in secondary hyperthyroidism.

In order to diagnose secondary hyperthyroidism, a healthcare professional will first do a physical exam and get a detailed medical history. They may also ask about:

  • your symptoms, when they started, and if anything makes them better or worse
  • any other medical conditions you’ve been diagnosed with
  • any medical conditions that run in your family
  • the medications and supplements that you’re taking

Blood tests can be used to check your thyroid function. These can measure levels of TSH and thyroid hormone and require collecting a small sample of blood from a vein in your arm.

A doctor may also want to do a blood test for thyroid autoantibodies as well. This is to check for Graves’ disease, an autoimmune condition that’s the most common cause of hyperthyroidism.

Having TSH and thyroid hormone levels that are higher than normal in the absence of thyroid autoantibodies can suggest secondary hyperthyroidism.

Imaging tests like MRI scans or CT scans can help to confirm the presence of a tumor affecting the pituitary gland.

Surgery is the main treatment option for thyrotropin-releasing pituitary adenomas. The goal is to remove as much of the tumor as possible.

Surgery for pituitary tumors is typically done endoscopically through your nasal passages. This involves the surgeon making a small cut in one of your sinuses, allowing the endoscope to access your pituitary gland.

If you’re eligible for surgery, you’ll likely be given a somatostatin analogue drug beforehand. This can help slow the production of TSH caused by the tumor. It also helps to restore thyroid levels to normal and could also shrink the tumor.

Following surgery, it’s possible to develop hypothyroidism (low thyroid hormone). If this occurs, you can be given levothyroxine, a medication that can help increase your thyroid hormone to a healthy level.

Secondary hyperthyroidism can occur due to a benign tumor that makes excess TSH. This causes your thyroid gland to make too much thyroid hormone.

People with secondary hyperthyroidism often have typical symptoms of hyperthyroidism. They may also have other symptoms associated with pituitary tumors, like headaches and vision changes.

The main treatment for secondary hyperthyroidism is surgery to remove as much of the tumor as possible. This can help to reduce thyroid hormone levels to a healthy level.