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What Does TSH Measure?

TSH stands for thyroid stimulating hormone. The term TSH is often used to define the laboratory test administered by doctors to measure the levels of TSH in the body. TSH levels are used to help measure whether the pituitary gland and thyroid gland are working properly.

  1. TSH and the Pituitary

    • TSH is released by the pituitary gland in order to stimulate the thyroid to release two other hormones, called T3 and T4.

    High TSH

    • When results of a TSH test show high levels of thyroid stimulating hormone, it means that the pituitary gland is working overtime in an attempt to boost levels of T3 and T4 in the body. High levels of TSH result in a condition known as hypothyroidism.

    Low TSH

    • Low TSH levels mean that the pituitary is working less in order to stop the thyroid from producing as much T3 and T4. Low levels of TSH result in a condition known as hyperthyroidism.

    Causes for High TSH

    • The pituitary gland may secrete too much TSH if either the pituitary itself or the thyroid are damaged and not working as normal, if the thyoid is inflamed or infected or if the pituitary has been damaged due to an infection or tumor.

    Causes for Low TSH

    • Low TSH levels can be the result of a thyroid gland that secretes too much T3 or T4, an inflamed or infected thyroid, a thyroid that has grown too large, or by a tumor on the thyroid gland.

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