I did my own research and found a doctor who is an integrative doctor too, and he informed me that weak adrenals are definitely an issue if we want to use our thyroid hormones properly etc. The other common reason for people becoming hypo, is autoimmune disease e.g. Hashimoto’s. Here, the immune system itself attacks the thyroid. Sometimes the inflamed thyroid swells and makes huge spurts of thyroid hormone, so the person becomes hypEr, then hypO when the hormone levels go down, then hypEr, then hypO etc. Eventually thanks to the drugs used, radioactive iodine or surgery, or just the immune system attacking the hell out of the thyroid, the person becomes hypO permanently i.e.
low levels of thyroid hormone in the cells. There are other reasons for a thyroid becoming inflamed too, search research papers on google scholar and read widely. Hashimoto’s is quite common. A lack of iodine in the body can also lead to hypOthyroidism. If we are low in minerals and vitamins we cannot convert our thyroid hormones to use them. We can only use the active form of thyroid hormones. Conversion requires enzymes. Enzymes require a lot of quality raw materials i.e.vitamins and minerals.Hypo can be caused by inheriting the disease, deficiency, shock, stress, pregnancy, grief, divorce, surgery, big life changes, changing countries, hysterectomy, dieting especially if it’s repetitive dieting, skipping meals, avoiding food, weak adrenals, low iron and ferritin, low stomach acid (which typically shows as heartburn), low vitamin B12, folate etc.