 You have to look at iodine levels. Iodine is the number one trace mineral that causes the thyroid to work well. And if we get deficient in iodine, a lot of times the thyroid won't work. And Broda Barnes wrote an interesting book on the thyroid. He's a famous endocrinologist. You might want to look that up on Amazon. But just look up Broda Barnes. And I would look up and do some of the reading.