The thyroid gland is situated at the base of the neck. It is responsible for the proper functioning of the body’s metabolism. It maintains and regulates important bodily functions like breathing, heart rate, nervous system, menstrual cycle, temperature, cholesterol levels and more.
The different thyroid hormones
The important hormones related to thyroid function are:-
– Triiodothyronine (T3)
– Thyroxine (T4)
– Thyroid stimulating hormone (TSH)
T3 and T4 hormones are secreted by the thyroid gland and help in maintaining the metabolism. The TSH hormone is produced by the hypothalamus and the pituitary gland to help regulate T3 and T4 balance.
If T3 and T4 levels in the blood are low, more TSH is released to produce more T3 and T4 hormones. But, if hormone levels are high, less TSH is released and the production of the hormones is slowed down.
Important thyroid tests
To check the function of your thyroid, the levels of T4, T3 and TSH hormones have to be measured.
Thyroid stimulating hormone Test (TSH)
The normal, initial test for thyroid function is measuring the TSH level using a blood sample.
If the TSH level is high, it can be indicative of abnormal functioning of the thyroid gland. It means lesser hormones are being produced and this is called hypothyroidism.
If the TSH level is low, it can be pointing to an overactive thyroid and this condition is called hyperthyroidism.
Sometimes, a low TSH could be due to an abnormality in the pituitary gland that is preventing it from making adequate TSH.
The T4 test (Thyroxine test)
This test is done to measure the amount of free thyroxine, or T4, in your blood. Usually, the TSH and T4 will both be measured to arrive at a conclusion.
• A high level of TSH and low T4 could mean hypothyroidism due to disease in the thyroid gland.
• A low level of TSH and low T4 shows hypothyroidism that is caused by a problem involving the pituitary gland.
• A low TSH with a high T4 is indicative of hyperthyroidism.
The T3 test (Triiodothyronine)
The T3 tests are useful in diagnosing the severity of hyperthyroidism.
Usually, if there are any symptoms of a thyroid problem, your doctor will prescribe all the above basic three tests, to determine if you have a thyroid problem.