Thyroid Stimulating Hormone (TSH), otherwise also called thyrotropin, is a hormone secreted by the pituitary gland, a pea-shaped gland located at the base of the skull. TSH further regulates the production of Triiodothyronine (T3) and Thyroxine (T4) from the thyroid gland, a butterfly-shaped gland located at the bottom front of your neck.
TSH, T3 and T4 work together to regulate how your body uses energy — they play an important role in controlling your weight, body temperature, metabolism, muscle strength and nervous system.
Higher TSH levels in your blood report indicate hypothyroidism, meaning your thyroid gland isn't making enough T3 or T4 hormones. Similarly, lower levels of TSH indicate hyperthyroidism.
It's important to know that different doctors and labs have a varying "normal" range. However, most doctors and labs consider a range between 0.27 - 4.5 mlU/L to be normal.