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Thyroid hormones
TSH
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Thyroid stimulating hormone (TSH) is produced in the pituitary gland in order to regulate the production of thyroid hormones thyroxine (T4) and triiodothyronine (T3) by the thyroid gland. If thyroid hormones in the blood are low, then more TSH is produced to stimulate the thyroid gland to produce more of them. If thyroid hormone levels are high, then the pituitary produces less TSH to slow the production of thyroid hormones. If TSH is too high or too low, it normally signifies that there is a problem with the thyroid gland which is causing it to under or over produce thyroid hormones. Sometimes a disorder of the pituitary gland can also cause abnormal TSH levels.
Special instructions
How to prepare for your test
Prepare for your Thyroid Stimulating Hormone Blood Test by following these instructions. Take your sample between 6am and 10am. Do not take biotin supplements for two days before this test, discuss this with your doctor if it is prescribed. If you take thyroxine, you can take your medication as usual, either before or after your blood test. However, if you take desiccated thyroid extract (DTE) or liothyronine, it's best to take it after you've collected your sample. Please let us know in your supporting information if you take amiodarone or lithium as these can affect your thyroid function results.
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FAQs
What are the symptoms of a thyroid condition?
Symptoms of an overactive thyroid (hyperthyroidism) include heat intolerance, weight loss, heart palpitations and breathlessness. On the flip side, symptoms of an underactive thyroid (hypothyroidism) include fatigue, weakness, weight gain, slow heart rate, and cold intolerance.
Which hormones does the thyroid make?
Your thyroid produces hormones that affect almost every cell in your body. Thyroid hormones thyroxine (T4) and triiodothyronine (T3) help regulate the rate your body uses energy. Thyroid-stimulating hormone (TSH) is produced in the pituitary gland and regulates the production of T3 and T4. It is usually measured as a proxy for thyroid hormones T4 and T3. When circulating hormones are low, TSH elevates, and when circulating hormones are high, TSH will be low. Raised levels of TSH can indicate that the thyroid is struggling to produce sufficient quantities of thyroid hormones and is underactive. Low levels can show that the thyroid produces excess levels of thyroid hormones and is overactive.
What is a Thyroid Stimulating Hormone Blood Test?
Our Thyroid Stimulating Hormone Blood Test is an entry-level test for thyroid function that measures the amount of thyroid-stimulating hormone (TSH) in your blood. A TSH test is often the first test for evaluating thyroid function and symptoms of hyper or hypothyroidism.