Your Thyroid Explained

Most of us grow up with a vague sense that the thyroid does something with metabolism, and zero detail on the part that actually matters. Which is unfortunate, because thyroid problems are common, frequently under-diagnosed, and capable of causing a long list of symptoms that get blamed on stress, sleep, ageing, or "just being tired."

If you've ever been told your bloodwork is "normal" while still feeling off, or if cycles, fertility, energy, mood, weight, or hair have shifted in a way that doesn't quite track, your thyroid is worth investigating.

Start here

Your thyroid is a small butterfly-shaped gland in the front of your neck. Its job is to release two hormones, T4 (the storage form) and T3 (the active form), that set the pace for nearly every cell in your body. Heart rate, body temperature, how fast you burn calories, how cycles run, how brain cells fire, how skin and hair regenerate. All of it runs on thyroid hormone.

The brain tells the thyroid what to do through a signal called TSH (thyroid stimulating hormone). When thyroid hormone is low, TSH goes up, telling the gland to work harder. When thyroid hormone is high, TSH drops. That inverse relationship is why TSH is ...