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Spotlight on Thyroid Function

Conditions of the thyroid, be it underactive (hypothyroidism) or overactive (hyperthyroidism) have become increasingly more common through the years. It is anticipated by the American Thyroid Organization that greater than 12% of the American population will develop some condition related to the thyroid during their lifetime. Often many individuals go undiagnosed for years due to inadequate lab testing. This article focuses particularly on underactive thyroid or hypothyroidism.


What is Hypothyroidism?

Hypothyroidism is a condition where the thyroid gland does not produce sufficient amounts of thyroid hormone. Thyroid hormone is needed to regulate the body’s metabolism and plays an important role in functions related to the heart, digestion, brain, mood, and bone health.


What is the Cause?

The most common cause of hypothyroidism in America is Hashimoto’s, an autoimmune condition. In Hashimoto’s the body produces antibodies that slowly damage the thyroid gland.

Another potential cause is nutrient deficiencies, such as iodine. Iodine is needed to produce thyroid hormone and is obtained purely through the diet. With today’s trend of often consuming the more natural forms of salt, such as himalayan pink salt or sea salt, most people have insufficient levels of iodine. Some food sources for iodine include seaweed, shrimp, and iodized salt.

Additionally, a sometimes overlooked cause of hypothyroidism is environmental toxins. The thyroid gland has a great affinity for halogens such as iodine and metals making it particularly susceptible to environmental toxins. Some of the heavy metals noted to interfere with thyroid function include cadmium, lead, mercury, and aluminum. These are some of the causes of hypothyroidism.


What are Common Symptoms of Hypothyroidism?

The thyroid hormone binds to nearly every cell in the body. When there is an insufficient amount of thyroid hormone, this can lead to a wide array of symptoms. Some common clinical manifestations include:

  • Brain Fog

  • Brittle Nails

  • Cold Intolerance

  • Constipation

  • Depression

  • Dry Skin

  • Fatigue

  • Hair Loss/Thinning

  • Muscle Aches or Joint pain

  • Weight gain


What Lab Tests to Check?

As with many aspects of life, there may be some variation amongst practitioners regarding the preferred labs to order. Below are some labs I commonly check when an underactive thyroid condition is suspected as well as when monitoring the treatment of hypothyroidism. It’s important to have a full picture and understanding of the body in order to restore balance.


Thyroid stimulating hormone is produced by the pituitary gland in the brain. It regulates the production of thyroid hormone, T4 (thyroxine) and T3 (triiodothyronine), in the thyroid gland.

Free T4

This level indicates the amount of available T4 (thyroxine) in the body, which is ultimately converted into the more active form, T3.

Free T3

This level indicates the amount of available T3 (triiodothyronine), which binds the receptors of cells in the body. It regulates body temperature, heart rate, and metabolism.

Reverse T3

This is an inactive thyroid metabolite that is made from T4 when there is inflammation, toxicity, or elevated cortisol from chronic stress.

Thyroid Antibodies

In particular, thyroid peroxidase antibody and anti-thyroglobulin antibody. Elevations indicate a diagnosis of Hashimoto’s, an autoimmune condition. It would be beneficial to check if there is a family history of thyroid dysfunction as well as a personal or family history of an autoimmune condition.


It’s important to assess nutrient levels such as zinc, selenium, iodine, iron, vitamin D, B vitamins, and Vitamin C to name a few. These are among the many nutrients needed to both produce thyroid hormone as well as convert to the active form, T3.


Although the thyroid gland may be small in size, it is an important and integral factor to balancing and optimizing one’s health and wellness. There are many options for treatment including addressing the root cause, nutrient supplementation, and thyroid hormone medication.


Interested in a functional medicine consultation to assess your thyroid health? Please contact the office at 813-644-9384 or email at for more information or to schedule an appointment. Reshma Patel, M.D. is a Board certified physician using a functional medicine focus practicing in the Tampa Bay area in Florida. She is passionate about using nutrition and lifestyle choices to help heal the body.



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