A thyroid imbalance, such as an overactive or underactive thyroid, can lead to problems with your weight, energy and mood.
Symptoms of an overactive thyroid include weight loss, fatigue, irritability and difficulty sleeping. Whereas, symptoms of an underactive thyroid include weight gain, hair loss, forgetfulness and low mood.
Testing thyroid hormones and antibodies help identify any potential issues with the thyroid gland such as a thyroid imbalance or an autoimmune condition.
Despite a thyroid condition needing medical intervention, there are lifestyle changes you can make to help manage the symptoms and support your wellbeing.
The biomarkers included in a thyroid function test include TSH, T3, T4 and thyroid antibodies.
Thyroid stimulating hormone regulates the production of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). TSH controls the release of these hormones in the blood and is an indicator of how well the thyroid gland is working. It is tested to check for an overactive or underactive thyroid.
Thyroxine (T4) is measured alongside TSH and T3 to help identify thyroid issues. High levels of T4 is due to an overactive thyroid, whereas low levels are due to an underactive thyroid.
T3 is the more active form of thyroxine and like T4 it is measured to identify whether the thyroid is working properly. It is used to diagnose an overactive thyroid.
Thyroglobulin is a large protein stored in the thyroid gland and aids the production of both T3 and T4. Raised levels of thyroglobulin antibodies are associated with autoimmune diseases that affect the thyroid.
Thyroid peroxidase antibodies (TPO) are a biomarker used to detect the presence of autoimmune thyroid disease. These antibodies develop when the immune system mistakes the components of the thyroid gland or its proteins as foreign. Therefore, if thyroid disease is present, TPO antibody levels will be high.
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Thyroid-stimulating hormone (TSH) is produced by the pituitary gland and acts on the thyroid to stimulate it to produce the hormones thyroxine and triiodothyronine.
An overactive thyroid, also known as hyperthyroidism, means you have too much thyroid hormone acting on the cells in your body which speeds them up. Their increased function can cause a variety of symptoms, such as anxiety, fast heartbeat, weight loss, sleep disturbances, trembling, and excessive sweating.
Thyroid conditions can be caused by autoimmune diseases where your immune system mistakenly attacks its own cells resulting in an immune response and some unpleasant symptoms.
Graves’ disease, for example, causes hyperthyroidism or an overactive thyroid. Because your immune cells attack the thyroid, it causes it to produce more thyroid hormones than your cells need and speeds up the rate at which they work. Whereas Hashimoto’s disease is an autoimmune condition that causes an underactive thyroid (hypothyroidism). It occurs when your immune system attacks the thyroid causing damage which results in not enough thyroid hormones being produced and slowing down your cells’ metabolism.
Triiodothyronine, also known as T3, is a hormone produced by your thyroid and affects nearly all of the processes in the body. It helps to regulate your metabolism, so how fast or
slow your cells work.
An underactive thyroid is also known as hypothyroidism and is caused by a lack of thyroid hormones. Because there aren’t enough thyroid hormones being made, the activity of your cells slows down and causes symptoms such as weight gain, low mood, and forgetfulness.
TSH – 0.27-4.2 mIU/L
Thyroxine (FT4) – 12-22 pmol/L
Triiodothyronine (FT3) – 3.1 – 6.8 pmol/L
Please note reference ranges can vary by lab and analytical process.
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