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Thyroid 101

Updated: Jul 20, 2022

Achy joints, decreased concentration, weight gain, low mood, hair loss, low immune function, irregular periods, decreased motivation and decreased energy are just some of the symptoms of low thyroid function. Unfortunately, many individuals feel low thyroid symptoms, but when they ask their doctor to run labs they are told “everything is normal.”

How is it possible to have so many symptoms of low thyroid and still have “normal labs?”

Many conventional medical providers are taught to do a simple screening test, checking just one or two lab values. If these values are “in the normal range” then patients are informed that either their symptoms have nothing to do with thyroid function or that there is nothing wrong. Unfortunately, most conventional medical providers do not test for active thyroid hormone levels and do not consider nutritional levels, stress levels or symptoms as part of the diagnostic process.

At Elevate Functional Medicine we understand that sub-optimal thyroid function is real, and we perform in depth lab testing to help uncover the underlying cause of symptoms. We understand that lab values are only part of the picture, and we value your symptom profile as an important part of your work up. To understand more about how the thyroid works, keep reading.

TSH and T4

The thyroid gland sits right at the base of the neck and is responsible for releasing thyroxine (T4). The amount of T4 made by the thyroid is dependent on thyroid stimulating hormone (TSH), which is secreted by the pituitary gland and regulates thyroid activity.

T4 is an inactive hormone, meaning that it does not bind to thyroid receptors. T4 has two jobs. Its primary job is the feedback loop -- to go back and tell the pituitary glad that the thyroid is working. Its second job is to be available to convert into triiodothyronine (T3). T3 is the active thyroid hormone.

T4 and T3

Every single cell in the body has thyroid receptors which are responsible for helping regulate cellular metabolism, heat production and the function of almost all the tissues and systems in the body. Much of the work of thyroid hormones is done when free T3 binds to thyroid receptors. T4 is converted into T3 in the thyroid gland, in tissues and in cells. This conversion is dependent on appropriate levels of vitamin D and iodine and is performed by enzymes which are made from the mineral selenium.

Stress, nutrition and thyroid hormones

Stress can come in many forms to the body – nutritional deficiencies, hormone imbalance, starvation, infection, prolonged decreased sleep, anxiety, environmental pollutants, and hormone disruptors to name just a few.

When the body is under stress it works to preserve energy production and goes into “stress mode.” Physical stress can decrease the conversion of T4 into the active free T3 – the body’s way of preserving energy which needs to be spent elsewhere. Cortisol levels (the fight or flight hormone) increase under stress and can interfere with thyroid hormone function at the receptor site. Studies have shown that there is a clear relationship between cortisol levels and TSH. Interestingly, low cortisol levels also impact thyroid hormone function and thyroid receptor sensitivity. Understanding the interplay of the stress response and how it impacts thyroid function is an essential part of a complete thyroid evaluation.

Thyroid hormone conversion is dependent on certain nutrients such as selenium, iodine and vitamin D. The word iodine is actually even in the name of T3 (triiodothyronine). In the United States, vitamin D and iodine deficiencies are among the top nutritional deficiencies seen. However, before starting to take supplements, it is essential to complete lab testing and know your actual levels. Replacing individual nutrients without knowing levels or how to safely proceed can lead to potential side effects or create unintended imbalances.


Treating thyroid disorders requires much more than prescribing a pill and checking a TSH level. A complete thyroid work up includes a detailed history, symptom review, advanced lab testing, diet and lifestyle evaluation. If you are diagnosed with hypothyroidism, are taking medication and still feel out of balance, trust your symptoms. If you are not diagnosed with a thyroid disease you may be suffering from low thyroid function at the cellular level. If you have symptoms of low thyroid function, listen to your body and work with a provider that does the same.

Gina Ditta-Donahue is a certified Family Nurse Practitioner and Anti-Aging Medicine provider. She specializes in helping people identify the root cause of symptoms and uses a functional and integrative approach to healing the whole person. She is co-founder of Elevate Functional Medicine.


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