The thyroid is a butterfly-shaped organ situated in our throat, near the windpipe and voice box. It’s a gland, which means its main function is to produce and secrete hormones. The hormones associated with the thyroid are T3 and T4; they’re often referred to as “metabolic hormones” because they influence our basal metabolic rate, or how much energy we consume at rest.
T3 and T4 are also involved in the production of proteins from when we’re fetuses in development through childhood; they are also instrumental in the healthy development of our nervous system and its continued support through adulthood. T3 and T4 even have intricate relationships with our reproductive hormones. If the levels of these hormones in our bodies are skewed, it can have an affect on our sex drive, fertility, and other reproductive behaviors as well.
But how are the levels of these hormones regulated in the body? The answer lies in the pituitary, a gland found in the brain. It produces a hormone called thyroid stimulating hormone (TSH). When levels of T3 and T4 in the body are low, the pituitary will produce and secrete more TSH, which will in turn instruct your thyroid to make more of its hormones. And if the levels of T3 and T4 circulating in the body are too high, the pituitary will produce and secrete less TSH. If your doctor suspects you have a thyroid issue, they may order a TSH test, which is a blood test that measures the amount of TSH in your blood. If your levels of TSH are too low or high, it could suggest that you have a thyroid condition.