The thyroid gland secretes T4 in response to TSH and the body’s needs for thyroid hormones. However, many patients don’t adequately convert the prohormone, T4, into the more active hormone, T3. When this conversion is not happening adequately, symptoms of hypothyroidism will ensure – even with a “normal” TSH! Therefore, our approach to treating thyroid dysfunction with thyroid hormone is to use a combination of T3 and T4 hormones and optimize the T4 to T3 conversion. This approach has been shown in the literature to be more effective than using T4 alone and patients prefer combined therapy.
The thyroid gland secretes T4 in response to TSH and the body’s needs for thyroid hormones. However, many patients don’t adequately convert the prohormone, T4, into the more active hormone, T3. When this conversion is not happening adequately, symptoms of hypothyroidism will ensure – even with a “normal” TSH! Therefore, our approach to treating thyroid dysfunction with thyroid hormone is to use a combination of T3 and T4 hormones and optimize the T4 to T3 conversion. This approach has been shown in the literature to be more effective than using T4 alone and patients prefer combined therapy.
It makes sense to use a combined T4/T3 product when you understand thyroid physiology. Why are some doctors opposed to this method of treatment?

Traditionally – perhaps because of large pharmaceutical companies, doctors have been trained to test only the TSH and occasionally the T4 levels and thus, replace only the T4 hormones. There was a met analysis (review of 9 individual studies) performed by Joffe RT et. al. that was sponsored by a pharmaceutical company that revealed no significant difference in psychiatric symptoms when T4 alone or T4/T3 was used. Our criticism of this study is that many of the papers they examined were not using a high enough dose of T3(only 5 ug of T3) to even make of difference. So, of course, the conclusion of the paper was that there was no benefit to using a combined regimen.
It makes sense to use a combined T4/T3 product when you understand thyroid physiology. Why are some doctors opposed to this method of treatment?

Traditionally – perhaps because of large pharmaceutical companies, doctors have been trained to test only the TSH and occasionally the T4 levels and thus, replace only the T4 hormones. There was a met analysis (review of 9 individual studies) performed by Joffe RT et. al. that was sponsored by a pharmaceutical company that revealed no significant difference in psychiatric symptoms when T4 alone or T4/T3 was used. Our criticism of this study is that many of the papers they examined were not using a high enough dose of T3(only 5 ug of T3) to even make of difference. So, of course, the conclusion of the paper was that there was no benefit to using a combined regimen.

In the traditional medical community, there is a lot of concern that suppressing the TSH will cause medical conditions such as osteoporosis and atrial fibrillation. It is true that endogenous hyperthyroidism (patients developing hyperthyroidism on their own – not treating hypothyroidism) is associated with osteoporosis. There is medical literature on both sides of the fence as to whether bone loss occurs or not with suppressed levels of TSH. We monitor bone turnover closely in our patients who have a suppressed TSH.