What is a Thyroid-Stimulating Hormone?

Thyroid-stimulating hormone is a hormone which is released by the pituitary gland to encourage the thyroid to increase its production of hormones. This hormone is also known as thyrotropin or TSH. When people have thyroid disorders, there may be abnormal levels of TSH in the blood. For this reason, when a doctor suspects that a patient may be experiencing impairments related to thyroid function, one of the first diagnostic tests is often a blood test to assess hormone levels.

The pituitary gland regulates the thyroid through the use of a feedback loop. The thyroid produces hormones such as triiodothyronine and thyroxine, and these hormones circulate through the blood. Some are delivered to the pituitary, which uses the hormone levels to determine whether or not the thyroid is making enough hormones.

If the thyroid is sufficiently active, the pituitary gland does not need to take any additional action. However, if the thyroid is underproducing, the pituitary makes thyroid-stimulating hormone and the hormone is delivered to the thyroid. The hormone acts to excite the thyroid so that it will make more hormones, restoring the endocrine balance. Thyroid-stimulating hormone levels are high in the blood when a patient's thyroid is not making enough hormones because the pituitary gland is trying to kickstart the thyroid into action.

The threshold at high thyroid-stimulating hormone levels start to be a cause for concern is actually a cause for some debate. As a general rule, doctors agree that if the levels are marginally high, the patient may be at risk of hypothyroidism and should be monitored. If the levels are abnormally high, steps may need to be taken to address the problem. One thing which patients should be aware of is that many things can alter the blood test results, so patients should disclose their dietary habits and all medications, including over the counter medications, before the test is performed.

Patients with thyroid disorders can be treated with medications, including hormones to compensate for the hormones which the body is not making. In some cases, patients may be given thyroid-stimulating hormone for therapeutic use if their thyroids are underactive or there is a problem with the pituitary gland and the thyroid is not being properly regulated. When hormones are prescribed, the patient will need to undergo regular testing because it is often necessary to adjust the dosage over time. An endocrinologist usually supervises the administration of hormones.