Fast Facts: Your Thyroid
- The thyroid is a small, butterfly-shaped gland in the front of the neck below the larynx, or voice box.
- The thyroid gland makes two thyroid hormones, triiodothyronine (T3) and thyroxine (T4).
- Thyroid hormones affect metabolism, brain development, breathing, heart and nervous system functions, body temperature, muscle strength, skin dryness, menstrual cycles, weight, and cholesterol levels.
- The level of thyroid hormone being made is usually controlled by a chemical made in the pituitary gland called thyrotropin, commonly known as Thyroid Stimulating Hormone (TSH).
- TSH and T3/T4 typically move in opposite directions.
- When your thyroid is producing too much thyroid hormone (hyperthyroidism), T3 and T4 are too high, and TSH will become low or undetectable, as the body doesn't need any additional thyroid hormone.
- When your thyroid is not producing enough thyroid hormone (hypothyroidism), TSH will increase, as the pituitary tries to stimulate the thyroid to produce more hormone.