Because, there is No Perfect Thyroid Test. Thyroid blood tests are not completely accurate and usually do not tell what the cause of the condition is. What is the value of solely using TSH, T3, T4 or even Reverse T3 and antibodies as one’s diagnostic yard-stick, when this health issue goes far beyond simply a thyroid gland dysfunction or failure?
This is a big reason why most endocrinologists and other types of medical doctors simply recommend thyroid hormone for people with hypothyroidism and Hashimoto’s Thyroiditis, or anti-thyroid drugs/RAI for people with hyperthyroidism and Graves’ Disease. They simply are not taught how to find the cause of most thyroid conditions and so the only thing they know is give their patients prescription drugs to manage the symptoms, or radioactive iodine in hyperthyroid conditions to obliterate the thyroid gland.