The thyroid drug Synthroid (levothyroxine sodium), as the name implies, is anything but natural. It is not bio-equivalent to the natural hormone thyroxine, but is instead a synthetic, hormone-like substance with very different properties.
In conventional medical treatment for hypothyroidism, once blood variables fall into a range deemed "normal" thanks to the introduction of synthetic chemicals, the "treatment" is deemed a success. Unfortunately, the quality of life of the patient may actually worsen as the synthetic chemicals compete with the remaining natural hormones still being produced by their thyroid.
According to Green Med Info:
"We know that 'lack of Synthroid' is NOT the cause of any thyroid problem. Exposure to chemicals, e.g. perchlorate, common food intolerances (e.g. wheat/dairy), adrenal fatigue and nutrient deficiencies are the cause of 'hypothyroidism' in the vast majority of cases. So let's get back to the work of figuring out how to address the problem naturally."