In health, what happens when your tissues don’t convert enough T4 into T3 hormone? Your healthy thyroid secretes more T3. The healthy thyroid gland’s synthesis of T3 de novo (from raw materials of iodine and tyrosine) under the stimulation of a healthy TSH can maintain your circulating T3 supply. This prevent tissues from becoming hypothyroid when they can’t convert enough T4 into T3 locally. This principle has been demonstrated in human models in Pilo’s study in 1990, and several other scientific studies. It is “the capacity of the hypothalamic-pituitary-thyroid axis to compensate for the lack of peripheral T4-to-T3 conversion.” (Marsili …