Understanding the Thyroid Gland: Your Body’s Metabolic Powerhouse

(Audio) Understanding the Thyroid Gland

0:00

The thyroid gland may be small, but it plays a massive role in your overall health. Located at the front of your neck, this butterfly-shaped gland is part of your endocrine system and is responsible for producing hormones that regulate your metabolism, energy levels, and more [1].

What Does the Thyroid Gland Do?

The thyroid produces and releases several key hormones, primarily thyroxine (T4) and triiodothyronine (T3). These hormones influence how your body uses energy, controls temperature, and supports vital functions like heart rate and digestion [2]. While T4 is the most abundant, it is largely inactive until converted into T3, the more active form that directly affects your cells and metabolism.

You may also have heard of reverse T3 (rT3), which is an inactive metabolite of thyroxine (T4) that is produced when the body converts T4 in a way that blocks thyroid hormone activity, often as a response to stress, illness, or calorie restriction [3,4,5]. Another hormone, calcitonin, is also produced by the thyroid and helps regulate calcium levels in the blood, although it doesn’t impact metabolism like T3 and T4 [2].

Why Are Healthy Thyroid Hormones Important?

Thyroid hormones are essential for:

• Metabolic regulation: They determine how efficiently your body converts food into energy.

• Growth and development: Especially critical in infants and children for brain and physical development.

• Mood and mental clarity: Imbalances can lead to symptoms like depression, anxiety, or brain fog.

• Heart and digestive function: They help maintain a steady heart rate and support digestive processes.

• Reproductive Health: Thyroid hormones play a vital role in reproductive health for both women and men. In women, thyroid dysfunction can disrupt menstrual cycles, ovulation, and fertility, while in men it can impair testosterone production, sperm quality, libido, and erectile function. Both hypothyroidism and hyperthyroidism are associated with reduced fertility and hormonal imbalances that affect reproductive outcomes [6,7,8,9].

When the thyroid is underactive (hypothyroidism) or overactive (hyperthyroidism), it can lead to a wide range of health issues, from fatigue and weight gain to anxiety and heart palpitations [10].

Supporting Thyroid Health

Maintaining a healthy thyroid involves:

• Getting proper nutrients needed to produce thyroid hormones.

• Managing stress, which can disrupt hormone balance.

• Addressing any underlying inflammation that could affect thyroid function.

• Supporting digestive health for optimal thyroid function.

• Regular thyroid screenings, especially if you have a family history of thyroid disorders.

Disclaimer: The information provided in this article is for informational and educational purposes only and is not intended as medical advice, diagnosis, or treatment. Always consult with a qualified healthcare provider before making changes to your diet, lifestyle, or health care regimen.

References

1. Cleveland Clinic. Thyroid: What It Is, Function & Problems. Cleveland Clinic. https://my.clevelandclinic.org/health/body/23188-thyroid. Accessed June 7, 2025.

2. Cleveland Clinic. Thyroid Hormone: What It Is & Function. Cleveland Clinic. https://my.clevelandclinic.org/health/articles/22391-thyroid-hormone. Accessed June 7, 2025.

3. Peeters RP, Wouters PJ, Kaptein E, et al. Reduced activation and increased inactivation of thyroid hormone in tissues of critically ill patients. J Clin Endocrinol Metab. 2003;88(7):3202-3211. doi:10.1210/jc.2003-030244

4. Chopra IJ. The nonthyroidal illness syndrome or “euthyroid sick syndrome.” Endocr Pract. 1996;2(1):45-52. doi:10.4158/EP.2.1.45

5. Wartofsky L, Burman KD. Alterations in thyroid function in patients with systemic illness: the “euthyroid sick syndrome.” Endocr Rev. 1982;3(2):164-217. doi:10.1210/edrv-3-2-164

6. Krassas GE, Pontikides N. Male reproductive function in relation with thyroid alterations. Best Pract Res Clin Endocrinol Metab. 2004;18(2):173-183. doi:10.1016/j.beem.2004.03.001

7. Carani C, Isidori AM, Granata AR, et al. Multicenter study on the prevalence of sexual symptoms in male hypo- and hyperthyroid patients. J Clin Endocrinol Metab. 2005;90(12):6472-6479. doi:10.1210/jc.2005-1327

8. Krassas GE, Poppe K, Glinoer D. Thyroid function and human reproductive health. Endocr Rev. 2010;31(5):702-755. doi:10.1210/er.2009-0041

9. Poppe K, Velkeniers B. Thyroid disorders in infertile women. Ann Endocrinol (Paris). 2003;64(1):45-50. doi:10.1016/S0003-4266(03)00004-5

10. Cleveland Clinic. Thyroid Disease: What It Is, Causes, Symptoms & Treatment. Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/8541-thyroid-disease. Accessed June 7, 2025.

©2025 by Nazanin Safaei, ND, MS