Thyroid-stimulating hormone, thyrotropin or TSH is a hormone produced by the pituitary gland that stimulates the production of hormones by the thyroid gland. The release of TSH is similarly regulated by thyrotropin-stimulating hormone produced by the hypothalamus. The level of TSH in the blood is usually measured in relation to thyroid hormones - if one is high the other should be low and vice versa. Consistently high or low levels of both are usually an indication of another disease, such as a tumor on the pituitary or hypothyroidism.