A thorough dive into what your thyroid does and why
Let’s speak about thyroid function. The thyroid gland is one of the major hormone-secreting (endocrine) glands in the body. It is a small butterfly-shaped gland located in front of the windpipe at the base of the throat.
It is composed of two conical right and left lobes that are joined at the front by a central bridge called the isthmus. The thyroid gland is the largest gland of the endocrine system weighting between 15–25g.
The thyroid gland produces two hormones, thyroxine (T4) and triiodothyronine (T3), which are secreted into the blood. These hormones have a vital role in growth and metabolism by regulating the functions of the cardiac, digestive and muscular systems, as well as maintaining healthy bones and normal brain development.
Iodine is needed for the production of thyroid hormones. As iodine is not produced by the body, it needs to come from dietary sources — predominantly seafood and iodized salt. It is thought that up to 30% of people worldwide are iodine deficient. Iodine is particularly important during early pregnancy to help prevent adverse neurodevelopmental outcomes in offspring, as well as in young children.
The stimulation of the thyroid gland occurs as a part of the hypothalamic–pituitary–thyroid axis.
The hypothalamus, located in the brain, secretes a hormone called thyroid-releasing hormone. This hormone then stimulates the pituitary gland, which is located below the hypothalamus, to release a hormone called thyroid-stimulating hormone (TSH) and it is TSH that triggers the thyroid gland to secrete thyroid hormones.
The production of thyroid hormones is tightly controlled by a feedback loop: if the pituitary gland senses an excess of T3 and T4 in the system, TSH production is reduced, which in turn results in reduced T3 and T4 production by the thyroid gland.
By contrast, if there are low levels of thyroid hormones in the bloodstream, the pituitary gland produces more TSH that stimulates the thyroid gland to secrete more hormones to keep up with the body’s demand.
The majority of T3 and T4 circulating in the body are bound to transport proteins and only very small amounts of T3 and T4 are available as free hormones (unbound) and can directly enter the body’s cells. The thyroid produces more T4 than T3, and much of T3 found in the body has been converted from T4 in a process called deiodination.
The primary test (thyroid function test) to check whether the thyroid gland is functioning properly measures TSH and free (unbound) T4 levels. High TSH and low T4 levels can indicate an underactive thyroid gland, whereas an overactive thyroid gland can present as low TSH and high T4 levels.
If you are interested in getting your Thyroid levels checked, you can order one of our kits here.
Thyroid hormones affect all organs and systems in the body, including the heart, gastrointestinal system, nervous system, bone and metabolism.
Thyroid Hormones undertake the following functions in your body:
An overactive thyroid gland, also known as hyperthyroidism, results in an excess of T3 and T4 and, consequently, decreased levels of TSH. This condition is characterised by increased metabolism and symptoms include:
Graves’ disease: an autoimmune disease where the thyroid becoming overactive and produces excessive amounts of thyroid hormones. It is the most common cause of hyperthyroidism.
Thyroid nodules: usually benign (non-cancerous) nodules or lumps that may contain thyroid tissue, which can result in the production of excess thyroid hormones.
Medicines: medications with high iodine content, such as some antiarrhythmic medicines that are used to control irregular heartbeats, can cause hyperthyroidism.
Thyroiditis: inflammation of the thyroid gland can cause excessive production of thyroid hormones.
Underactive thyroid is also known as hypothyroidism. It is a condition in which the thyroid gland does not produce enough thyroid hormones to meet the body’s demand and coincides with increased TSH levels. Thyroid-hormone deficiency results in slower metabolism and this may cause the following symptoms:
Hashimoto’s disease: an autoimmune disease in which the thyroid gland becomes inflamed and stops making enough thyroid hormones. It is the most common cause of hypothyroidism.
Thyroiditis: inflammation of the thyroid gland initially causes hyperthyroidism but over time the thyroid gland becomes damaged causing thyroid hormone deficiency.
Surgical removal of part of the thyroid: sometimes after removing part of the thyroid, the remaining tissue stops making thyroid hormones resulting in hypothyroidism.
Radiation therapy: used to treat hyperthyroidism by destroying thyroid cells but can eventually result in hypothyroidism.
Medications: some medicines such as cancer, heart and psychotic medications can interfere with the production of thyroid hormones.
If you would like to get find out more about your Thyroid levels, check out our Home Testing kit here
References
Transform the way you approach your health with Hibernian Health Check’s convenient and accurate home blood test kits. In this post, we are answering the Top 10 Questions about Home Blood Testing Kits!
AMH stands for Anti-Müllerian Hormone and it is commonly viewed as a biomarker for ovarian reserve. The term ‘ovarian reserve’ refers to the reproductive potential in the ovaries based on the number and quality of follicles and oocytes (potential eggs) contained within.
A thorough dive into what your thyroid does and why
Let’s speak about thyroid function. The thyroid gland is one of the major hormone-secreting (endocrine) glands in the body. It is a small butterfly-shaped gland located in front of the windpipe at the base of the throat.
It is composed of two conical right and left lobes that are joined at the front by a central bridge called the isthmus. The thyroid gland is the largest gland of the endocrine system weighting between 15–25g.
The thyroid gland produces two hormones, thyroxine (T4) and triiodothyronine (T3), which are secreted into the blood. These hormones have a vital role in growth and metabolism by regulating the functions of the cardiac, digestive and muscular systems, as well as maintaining healthy bones and normal brain development.
Iodine is needed for the production of thyroid hormones. As iodine is not produced by the body, it needs to come from dietary sources — predominantly seafood and iodized salt. It is thought that up to 30% of people worldwide are iodine deficient. Iodine is particularly important during early pregnancy to help prevent adverse neurodevelopmental outcomes in offspring, as well as in young children.
The stimulation of the thyroid gland occurs as a part of the hypothalamic–pituitary–thyroid axis.
The hypothalamus, located in the brain, secretes a hormone called thyroid-releasing hormone. This hormone then stimulates the pituitary gland, which is located below the hypothalamus, to release a hormone called thyroid-stimulating hormone (TSH) and it is TSH that triggers the thyroid gland to secrete thyroid hormones.
The production of thyroid hormones is tightly controlled by a feedback loop: if the pituitary gland senses an excess of T3 and T4 in the system, TSH production is reduced, which in turn results in reduced T3 and T4 production by the thyroid gland.
By contrast, if there are low levels of thyroid hormones in the bloodstream, the pituitary gland produces more TSH that stimulates the thyroid gland to secrete more hormones to keep up with the body’s demand.
The majority of T3 and T4 circulating in the body are bound to transport proteins and only very small amounts of T3 and T4 are available as free hormones (unbound) and can directly enter the body’s cells. The thyroid produces more T4 than T3, and much of T3 found in the body has been converted from T4 in a process called deiodination.
The primary test (thyroid function test) to check whether the thyroid gland is functioning properly measures TSH and free (unbound) T4 levels. High TSH and low T4 levels can indicate an underactive thyroid gland, whereas an overactive thyroid gland can present as low TSH and high T4 levels.
If you are interested in getting your Thyroid levels checked, you can order one of our kits here.
Thyroid hormones affect all organs and systems in the body, including the heart, gastrointestinal system, nervous system, bone and metabolism.
Thyroid Hormones undertake the following functions in your body:
An overactive thyroid gland, also known as hyperthyroidism, results in an excess of T3 and T4 and, consequently, decreased levels of TSH. This condition is characterised by increased metabolism and symptoms include:
Graves’ disease: an autoimmune disease where the thyroid becoming overactive and produces excessive amounts of thyroid hormones. It is the most common cause of hyperthyroidism.
Thyroid nodules: usually benign (non-cancerous) nodules or lumps that may contain thyroid tissue, which can result in the production of excess thyroid hormones.
Medicines: medications with high iodine content, such as some antiarrhythmic medicines that are used to control irregular heartbeats, can cause hyperthyroidism.
Thyroiditis: inflammation of the thyroid gland can cause excessive production of thyroid hormones.
Underactive thyroid is also known as hypothyroidism. It is a condition in which the thyroid gland does not produce enough thyroid hormones to meet the body’s demand and coincides with increased TSH levels. Thyroid-hormone deficiency results in slower metabolism and this may cause the following symptoms:
Hashimoto’s disease: an autoimmune disease in which the thyroid gland becomes inflamed and stops making enough thyroid hormones. It is the most common cause of hypothyroidism.
Thyroiditis: inflammation of the thyroid gland initially causes hyperthyroidism but over time the thyroid gland becomes damaged causing thyroid hormone deficiency.
Surgical removal of part of the thyroid: sometimes after removing part of the thyroid, the remaining tissue stops making thyroid hormones resulting in hypothyroidism.
Radiation therapy: used to treat hyperthyroidism by destroying thyroid cells but can eventually result in hypothyroidism.
Medications: some medicines such as cancer, heart and psychotic medications can interfere with the production of thyroid hormones.
If you would like to get find out more about your Thyroid levels, check out our Home Testing kit here
References
Olive gained her PhD in Trinity College Dublin in Immunology. She has enjoyed a varied career including working as an immunologist, researcher, science communicator and Chief Editor for leading scientific journal, Nature Reviews Immunology. Olive has now set up her own business in sustainable forestry management but still maintains her passion for science and education through her articles with Hibernian Health Check.
Transform the way you approach your health with Hibernian Health Check’s convenient and accurate home blood test kits. In this post, we are answering the Top 10 Questions about Home Blood Testing Kits!
AMH stands for Anti-Müllerian Hormone and it is commonly viewed as a biomarker for ovarian reserve. The term ‘ovarian reserve’ refers to the reproductive potential in the ovaries based on the number and quality of follicles and oocytes (potential eggs) contained within.
