The thyroid gland is an integral part of the body’s endocrine system. This gland is found in the front portion of the neck, and is primarily responsible for the production of thyroxine and triiodothyronine, also known as thyroid hormone. In this article, we will be giving you a brief overview of the function of the thyroid gland, in addition to the hormones it produces.
Why is the Thyroid Gland So Important?
What Does Your Thyroid Do?
As mentioned, the thyroid gland is a part of the endocrine system. Given this, it is responsible for the maintenance of the hormone levels in the body. Aside from producing thyroid hormone, the thyroid actually helps regulate several other functions in the body. The following are a few examples of bodily processes involving the thyroid gland:
- Heart Rate
- Body temperature
- Rate of Burning Calories
Aside from the mentioned functions, the thyroid hormone also plays a significant role in fostering brain development and growth. It is for this reason, that thyroid function and iodine levels are monitored in children.
The Thyroid Gland Needs Iodine
The thyroid gland absorbs iodine, an element found in many of the foods that we eat. This iodine is then combined with tyrosine, and converted into the thyroid hormones thyroxine (T4) and triiodothyronine (T3). Following this, the thyroid hormones are then released into circulation which allows them to control the body’s metabolic functions. Given this, it is important that we do not neglect consuming iodine-rich foods such as seafood. Medical practitioners encourage this especially in pregnant women, young children, and individuals with existing thyroid problems.
What Hormones Does the Thyroid Gland Secrete?
As mentioned, there are two primary hormones released by the thyroid gland. T3 and T4 function together to regulate the body’s metabolic functions. Some examples of metabolic functioning are the ability to convert glucose into energy as well as digestion, and burning calories.
However, the production of thyroid hormones does not solely rely on the thyroid gland. The pituitary gland secretes a hormone called thyroid stimulating hormone (TSH) which dictates the amount of hormones that the thyroid gland ends up secreting. Doctors often request blood tests for those who are experiencing problems related to thyroid function in order to monitor the amount of TSH and thyroid hormones produced. In turn, the hypothalamus dictates the stimulation of the pituitary gland secretion by means of it releasing thyroid releasing hormone (TRH).
It is important to emphasize that the normal values for pregnant women and infants are significantly higher in comparison to non-pregnant adults. This is in connection with the need for thyroid hormones for brain development and growth.
Abnormalities in the amount of T3 present in blood circulation can be indicative of a dysfunctional thyroid. Approximately 20% of the total triiodothyronine in the bloodstream is from the thyroid gland. On the other hand, the remaining 80% is produced by means of the conversion of thyroxine by internal organs (e.g. liver and kidneys). T3 is the active hormone, T4 must be first converted into T3 prior to it being used. It functions primarily in delivering oxygen and energy to other cells. Upon blood examination, the normal range of results for T3 are the following:
- Total T3 – 80-200ng/dL
- Free T3 – 2.3-4.2 pg/mL
This is another key thyroid hormone and comprises the majority of the hormone that the thyroid gland produces. This hormone is regarded as a “storage hormone.” Furthermore, it must undergo a process called monodeiodination wherein, it loses an atom of iodine. Following the monodeiodination, T4 will then be converted to the usable T3. The following are the reference ranges for T4:
- Total T4 – 4.5-12.5 ug/dL
- Free T4 – 0.9-1.8 ng/dL
Often, doctors who request blood examinations do not test total T4 nor free T4. However, total T4 or free T4 readings that fall below the given reference range can be indicative of hypothyroidism. Another pertinent cause of hypothyroidism is a lack of the production and release of TSH. Conversely, elevated TSH and T4 levels can indicate the development of hyperthyroidism.
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In addition to T3 and T4, the thyroid gland also produces the hormone calcitonin. C cells, also known as parafollicular cells, secrete this particular hormone. These cells are next to the thyroid follicles and in connective tissue. C cells play a minor role in regulating the level of calcium and phosphate in your blood. Conversely, the amount of calcitonin is reliant on the amount of calcium in the blood. Should blood calcium levels decrease, so does the production of calcitonin. This process is necessary for the development of our bones.
Having an Excess of Thyroid Hormones
Thyrotoxicosis refers to an elevated amount of thyroid hormone in the bloodstream. The occurrence of this is often due to the over-stimulation of the thyroid gland which, in turn, refers to hyperthyroidism. Furthermore, this hyperthyroidism often occurs due to conditions such as Grave’s disease, thyroid inflammation, or a thyroid tumor. Given this, one of the first signs of thyrotoxicosis is the formation in the mass on the thyroid gland. The following are some other symptoms that often occur along with hyperthyroidism:
- Heat intolerance
- Weight loss
- Increased appetite
- Over-stimulation of bowel movement
- Irregular menstrual cycle
- Palpitations (rapid heartbeat)
- Hair Loss
- Retraction of Eyelids (eyes look larger, staring)
How Hypothyroidism Affects the Body
Hypothyroidism occurs when there is not enough available thyroid hormone. Additionally, hypothyroidism may be linked to a thyroid that has sustained damage. There are several causes for this condition:
- Autoimmune Disease
- Poor Iodine Intake
- Injury to Thyroid Gland
- Adverse Drug Reaction
Given that the thyroid hormones are an essential part of brain growth and development, this condition can be especially harmful for children. The permanent effects of hypothyroidism can come in the form of learning disabilities or stunted physical growth, among many other possible outcomes. Some of the symptoms associated with hypothyroidism in adults are the following:
- Intolerance to Cold Temperatures
- Slower Heart Rate
- Weight Gain
- Reduced Appetite
- Stiffness of Muscles (tetany)
If you want to learn more about the thyroid gland and the hormones that it secretes, watch this video by Armando Hasudungan.
The thyroid gland plays a major role in maintaining many of the body’s processes. We must actively include the condition of our thyroid and the hormones that it produces when evaluating our overall health. Should you feel any lumps in your neck or experience any of the symptoms related to abnormalities in thyroid hormone levels, consult with your doctor immediately.
Do you have any experience dealing with problems with your thyroid gland? Please feel free to share your thoughts with us in the comments section below!