Medically reviewed on August 17, 2022 by Jordan Stachel, M.S., RDN, CPT. Last updated March 12, 2023. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.
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The body is a complex system that carries out thousands of unseen processes every minute of every day. One of these essential processes revolves around the thyroid gland—a small, bowtie-shaped organ in the throat.
The thyroid works alongside other organs to generate the hormones that regulate your metabolism.  Under normal circumstances, the body naturally regulates these hormones. However, thyroid disease and other health issues can cause fluctuations to normal levels that can lead to further problems.
Fortunately, medical science has made it possible to regulate thyroid hormones. We’ll explain what thyroid hormones are, how they work, and how to regulate thyroid hormones through medications and lifestyle changes.
Hormones are naturally-occurring chemicals that circulate through the bloodstream. Their job is to communicate with and assign “tasks” to your various organs, tissues, and muscles so that the physical systems work in tandem. 
Thyroid hormones have one purpose in particular: controlling your metabolism.  Metabolism chiefly refers to the process of converting food and beverages into fuel for everything you do, from breathing and thinking to running and swimming. Put simply, the thyroid gland manufactures the hormones that regulate your body’s energy consumption.
The thyroid gland releases several different hormones when it’s functioning normally, some of which play a major role in your endocrine (or hormonal) health. Let’s take a quick look at each of them.
Triiodothyronine (T3) is arguably the most important hormone the thyroid produces. T3 is considered the “active” thyroid hormone—the one that directly regulates your metabolism by interacting with your tissues and organs.
Like other hormones, T3 can exist in two forms: 
Despite its importance, T3 only accounts for around 20% of the total thyroid hormones the thyroid gland produces.
Thyroxine (T4) is the inactive thyroid hormone. Its role is to regulate overall thyroid hormone levels.
Like T3, T4 can also be free or bounded.
T4 makes up the majority of your thyroid gland’s total thyroid hormone production—roughly 80%. Because your body needs T3 more than it needs T4, it converts the latter into the former. 
Unlike T3 and T4, thyroid-stimulating hormone (TSH) does not originate in the thyroid. Instead, it is produced and released by the pituitary gland. Your pituitary gland is a pea-sized organ that instructs the thyroid when to release T3 and T4. 
Together with free T3 and free T4, TSH is measured as part of a standard thyroid function test.
Your thyroid also produces calcitonin, a hormone that controls your body’s use of calcium.  While calcitonin is essential to your overall health, it’s not directly linked to thyroid hormone dysregulation.
The thyroid hormone production process starts with the hypothalamus. This tiny section of the brain helps coordinate your endocrine system—the “messenger” network that encompasses (among other things) your hormones, pituitary gland, and thyroid gland. 
When the hypothalamus receives a signal from the brain, it generates a separate hormone called thyroid-releasing hormone (TRH).
Once TRH reaches the pituitary gland, it tells it to produce and send out thyroid-stimulating hormone (TSH).
From there, TSH travels to your thyroid gland, stimulating it to release T3 and T4 into your bloodstream.
This process is controlled by a carefully balanced feedback loop: As your levels of T3 and T4 rise, you stop producing TRH. Over time, your body uses up the available T3 and T4 during the metabolic process. When these hormone levels begin to drop again, the system kicks back in, the hypothalamus resumes its creation of TRH, and the cycle continues. 
In this way, your endocrine system is responsible for ensuring that your hormone levels stay consistent. However, if any organ in that chain falls out of sync, thyroid hormones can rise or fall outside the optimal range. This can lead to thyroid issues like hyperthyroidism or hypothyroidism.
While the system that regulates thyroid hormone production is complex, modern science has found ways to help you maintain endocrine balance. Let’s touch on four ways thyroid hormone levels can be optimized through testing, medication, and lifestyle changes.
The first step to knowing whether your thyroid hormone levels are within normal ranges is measuring them. For that, there’s the thyroid function test.
Also known as a "thyroid panel," this blood test measures your T3, T4, and TSH levels. Some thyroid tests also check your thyroid peroxidase antibodies (TPO) to see if thyroid function is being suppressed.
Traditionally, thyroid function tests were performed in clinics, but at-home thyroid tests are now readily available.
If an initial blood test comes back indicating hormone levels outside the normal ranges, your healthcare provider may order more tests, including:
Once you’re aware of any abnormal results, you can take the recommended steps to address your thyroid hormone levels.
Because your physical systems are interconnected, your diet can impact your thyroid hormones. Although there is no specific diet for people with thyroid disease, there may be ways to influence your hormone levels by watching what you eat. 
To balance your thyroid hormones from home, you can try:
Be sure to talk with a healthcare provider before significantly modifying your diet.
In some cases, a healthcare provider may recommend taking medications or hormones to bring your thyroid hormone levels back to normal. Depending on the severity of a thyroid condition, you may need to take medications temporarily or permanently.
For an overactive thyroid (hyperthyroidism), your healthcare provider may recommend options like:
People who have an underactive thyroid (hypothyroidism) may need to take a hormone replacement called levothyroxine. As always, you should only take medications a healthcare provider has prescribed.
The negative effects of smoking on general health are well-documented. However, smoking cigarettes may also impact your hormone levels.
According to a 2021 study, smokers can have significantly lower TSH levels than non-smokers. Even so, former smokers may still be able to recover their thyroid hormone levels—studies show that ex-smokers and non-smokers both had higher TSH levels than habitual smokers. 
To that end, if you currently smoke, you may be able to return to normal hormone levels by quitting smoking for good.
As mentioned, thyroid hormones play a key role in keeping the metabolic system on track. Metabolism regulates countless bodily functions, including: 
Beyond regulating metabolism, the thyroid gland also affects humans’ growth and brain development.  So whether you’re pregnant, looking to quit cigarettes for good, or simply want to put your health and wellness first, developing an awareness of your thyroid health is vital for ensuring the body’s overall welfare.
The process of measuring thyroid hormones starts with taking stock of their levels. With an at-home Thyroid Test from Everlywell, you can measure your free T3, free T4, and TSH levels. You’ll also receive an accurate reading of your thyroid peroxidase antibodies (TPOab)—antibodies that can suppress normal thyroid function.
If you want to learn how to check your thyroid at home, we have you covered. Our simple at-home tests make it easy for you to take charge of your thyroid health. Take the test at your convenience, mail it off to our lab, and receive your results within a few days.