Thyroid-stimulating hormone is also commonly referred to as TSH. It is a hormone that is secreted by the pituitary gland and plays a vital role in regulating the thyroid gland's function. TSH levels are used to diagnose thyroid disorders such as hypothyroidism and hyperthyroidism. In addition to TSH, other synonyms for thyroid-stimulating hormone include thyrotropin, thyrotrophin, and thyroid-stimulating factor. These terms are often used interchangeably in scientific literature and medical discussions. When doctors measure TSH levels, they are looking for an indication of how well the thyroid gland is functioning. Levels that are too high or too low may indicate an underlying thyroid disorder that requires further investigation and treatment.