How Is Thyroid Disease Diagnosed?
Your doctor will request a set of blood tests called thyroid function tests. These check the levels of thyroid hormones and the level of the thyroid stimulating hormone in the brain. Depending on these results, your doctor may also check levels of antibodies which may affect the thyroid gland.
Underactive thyroid – there will be low levels of thyroxine but the thyroid stimulating hormone levels are high as the brain tries to encourage the thyroid gland to produce thyroxine
Overactive thyroid – there will be high levels of thyroxine but now the thyroid stimulating hormone levels will be low as the brain tries to stop thyroxine production.
Subclinical hypothyroidism – here the levels of thyroxine are normal, but the thyroid stimulating hormone levels are high, so your brain is having to produce more stimulating hormone to make enough thyroxine. This does not need treatment but will require monitoring with repeat blood tests as a proportion of people with this will go on to develop an underactive thyroid.
Thyroid function tests will be done