Posted by The thyroid gland is a small butterfly-shaped gland responsible for modulating metabolism and cardiovascular function via the actions on the central autonomic control (Warner & Mittag, 2012). The thyroid is also responsible for growth and development along with body temperature control. Certain hormones such as thyroxine (T4) is what is most abundantly produced by the thyroid gland and acts as a precursor because it will later be converted into a more active hormone, triiodothyronine (T3). Triiodothyronine regulates metabolic rate, heart function, digestion, muscle control, brain development and bone health (Taylor et al., 2018). The secretion of T3 and T4 is regulated by thyroid-stimulating hormone (TSH), which is released by the anterior pituitary gland in response to thyrotropin-releasing hormone (TRH) from the hypothalamus. Low levels of thyroid hormones result in increased TSH secretion in an attempt to stimulate the thyroid gland (Chiamolera and Wondisford, 2009).
When these hormones are overactive, a condition called hyperthyroidism occurs. Too much T3 and T4 can speed up metabolism rates resulting in rapid or irregular heartbeat, weight loss, nervousness, tremors and heat intolerance. On the other hand, hypothyroidism occurs when too little thyroid hormone such as T3 and T4 are being produced. The opposite effect seen in hyperthyroidism occurs in hypothyroidism: intolerance to cold, fatigue, dry skin and hair, weight gain and slow heart rate (Peters et al., 2024). Hypothyroidism can be classified as primary, secondary or tertiary depending on whether the dysfunction originates in the thyroid gland, pituitary or hypothalamus. The most common cause of hypothyroidism is usually genetics. Other cases may include autoimmune diseases, certain medications, radiation therapy or thyroid surgery depending on the individual’s health history.
In order to treat regular hypothyroidism, doctors will prescribe various medications. The most widely used medication is levothyroxine, a synthetic form of T4 that is later converted into T3 in peripheral tissues. Levothyroxine is preferred due to its stability, long half-life and predictable conversion to T3 in peripheral tissues. Since T4 levels influence TSH secretion, clinicians typically monitor TSH and free T4 levels in the blood to guide proper dosing and ensure the patient reaches a normal thyroid state. Inadequate dosing can result in persistent symptoms of hypothyroidism, while overtreatment may lead to symptoms resembling hyperthyroidism (Jonklass et al., 2014). Patients are usually advised to take the medication on an empty stomach and consistently at the same time each day, such as morning or night, to maximize absorption and effectiveness. Regular follow-up is essential, as individual response to treatment can vary based on factors like age, weight and other medical conditions.
The thyroid gland plays a vital role in maintaining the body’s metabolism, cardiovascular health and overall physiological balance through the production of T3 and T4 hormones. When these hormones are deficient, as seen in hypothyroidism, multiple systems in the body can be affected. Fortunately, synthetic hormones replacement therapy–particularly with levothyroxine–offers an effective and widely accessible treatment option. With proper diagnosis, monitoring and adherence to therapy, individuals with hypothyroidism can manage their condition and maintain a good quality life.
References
Chiamolera, M. I., & Wondisford, F. E. (2009). Minireview: Thyrotropin-releasing hormone and
the thyroid hormone feedback mechanism. The Journal of Clinical Endocrinology & Metabolism, 94(4), 1472–1472. https://doi.org/10.1210/jcem.94.4.9997
Jonklaas, J., Bianco, A. C., Bauer, A. J., Burman, K. D., Cappola, A. R., Celi, F. S., Cooper, D.
S., Kim, B. W., Peeters, R. P., Rosenthal, M. S., & Sawka, A. M. (2014). Guidelines for the treatment of hypothyroidism: Prepared by the American Thyroid Association Task Force on Thyroid Hormone Replacement. Thyroid, 24(12), 1670–1751. https://doi.org/10.1089/thy.2014.0028
Peters, T., Medici, M., Hubalewska-Dydejczyk, A., & Boelaert, K. (2024). Hypothyroidism. The
Lancet, 404(10460).
Taylor, P. N., Albrecht, D., Scholz, A., Gutierrez-Buey, G., Lazarus, J. H., Dayan, C. M., &
Okosieme, O. E. (2018). Global epidemiology of hyperthyroidism and hypothyroidism. Nature Reviews Endocrinology, 14(5), 301–316. https://doi.org/10.1038/nrendo.2018.18
Warner, A., & Mittag, J. (2012). Thyroid hormone and the central control of homeostasis.
Journal of Molecular Endocrinology, 49(1). https://doi.org/10.1530/jme-12-0068
The thyroid gland is responsible for controlling your metabolism, cardiovascular functions, growth and development, and body temperature. T4 (thyroxine), which is later converted into T3 (triiodothyronine), is profusely produced by the thyroid gland. T3 regulates heart function, metabolic rate, digestion, muscle contraction, bone health, and brain development, so it’s essential. The hormones regulating T4 and T3 are thyroid-stimulating hormone (TSH), released by the anterior pituitary gland. Hypothyroidism occurs when the thyroid gland produces an imbalance of hormones, resulting in an increased secretion of TSH, which attempts to stimulate the thyroid gland. Hypothyroidism has too little T4 and T3, causing the metabolism to slow down, and Hyperthyroidism has too much T4 and T3, causing the metabolism to speed up. These conditions are the opposite of each other. The causes can be genetics, autoimmune disorders, reactions from medication, radiation therapy, or thyroid surgery. Levothyroxine is the primary medication used for treatment; it is a synthetic form of T4. With the use of synthetic hormones like, levothyroxine, people affected by hypothyroidism can maintain a good quality of life. Payton did a good job explaining her project, and her slide show provides visuals to help understand what hypothyroidism is and how it affects the body.