What Happens When You Have No Thyroid Gland?

If you don't have a thyroid gland, you may believe there is no information geared specifically towards you. For instance, you may come across information on hyper and hypothyroidism, but nothing about having no thyroid gland. This is a misunderstanding because if you don't have a thyroid gland, you are in fact hypothyroid and most information regarding hypothyroidism applies to you.

Even so, there are a couple unique considerations to keep in mind if you are "hypothyroid" with no thyroid gland, as opposed to "hypothyroid" from an under-functioning gland.

First, it's important to start with an overview of why some people are missing a thyroid gland. Here are the potential reasons:

• A small percentage of people are born without a thyroid or with a malformed thyroid, a condition known as congenital hypothyroidism.
• The treatment for thyroid cancer is usually surgical removal of all or part of the thyroid gland.
• Some people with thyroid nodules suspicious for cancer or a goiter (thyroid enlargement) that is cosmetically undesirable or affecting breathing or swallowing have the thyroid gland removed surgically.
• Some people with Graves' disease or hyperthyroidism from a toxic nodule or goiter (where too much thyroid hormone is being produced and released) have their thyroid removed surgically. 

The bottom line here is that if you don't have a thyroid gland at all, or you have a non-functioning thyroid gland, your condition is now hypothyroidism, irrespective of what disease or treatment led to the condition. 

In addition to those who were born without a thyroid gland, or who have had the gland surgically removed, there are other causes of hypothyroidism. These include: 

• Radioactive iodine (RAI) treatment for your Graves' disease or hyperthyroidism is also known as ablation therapy. RAI either greatly impairs or completely destroys your gland's ability to produce thyroid hormone, leaving you hypothyroid.
• Hashimoto's disease, an autoimmune condition where antibodies gradually destroy your thyroid's ability to produce hormone over time. 
• Medications, such as lithium, that damage your thyroid's ability to produce thyroid hormone.

While information on hypothyroidism applies to those with no thyroid, there are some special considerations for people without a thyroid gland.

Diet

If you were born without a thyroid, your thyroid has been surgically removed, or you have had total or near total ablation with RAI, you don't need to be concerned about goitrogenic foods (i.e., brussels sprouts, broccoli, kale etc.) and their ability to interfere with your thyroid function. You should, however, still be careful about overconsuming soy-based foods, as excessive soy intake may affect your ability to properly absorb your thyroid hormone replacement medication.

TSH Level Maintenance

Those without a functioning thyroid gland may find that they have fewer fluctuations in thyroid function and greater ease in keeping an optimal TSH level on a consistent medication dose, as compared to patients who still have a gland. (Patients who still have a gland find that it occasionally produces thyroid hormone, and can erratically increase or decrease its functioning, making it harder to regulate thyroid levels.)

Medications for Thyroid Cancer Patients

If you are a thyroid cancer patient who has had your thyroid gland removed, you are in a unique situation in that you are typically given thyroid hormone replacement drugs at "suppressive" levels. Suppression means taking a sufficient level of medication to keep your thyroid stimulating hormone (TSH) level very low or even undetectable. This is considered "hyperthyroid" by most lab standards, but suppression is necessary to prevent cancer recurrence in some patients.

In the end, while you may refer to yourself as "hyperthyroid," your underlying condition of having no thyroid gland means that you are actually hypothyroid, and much of the advice about hypothyroidism still applies to you.

A Word From Verywell

If you have no thyroid gland, information about hypothyroidism generally still applies to you. With that, if you are still experiencing thyroid symptoms after removal of your thyroid gland, you may need an adjustment of your thyroid hormone replacement medication.

Be sure to followup with your doctor as advised and proactively work with her to optimize your treatment and how you feel.