TSH is a hormone made in the pituitary gland to stimulate the thyroid to make thyroid hormone.
An elevated TSH level often means that the thyroid gland is not making enough thyroid hormone (poorly functioning thyroid). A decreased TSH level often means that the thyroid gland is overactive. This causes too much thyroid hormone to be produced.
TSH is requested to examine thyroid function or when there are symptoms of a thyroid that works too fast or too slow. It is often requested in combination with a determination of the thyroid hormones T4
TSH is determined to:
diagnose a thyroid dysfunction in a person with symptoms suggestive of a dysfunctional thyroid gland
monitoring the treatment of thyroid dysfunction and adjusting the dosage of thyroid hormone (L-thyroxine) if necessary