thyroxine index measured first thing in the morning nor any differences in the total T3 or free thyroxine index measured in the morning, we did, however, demonstrate a statistically significant difference in the response of the pituitary to a stimulus with a thyrotropin-releasing hormone. This difference in the TRH demonstrates that there is a difference in the bioavailability being detected only at the tissue level, in this case the pituitary.
Escalante and colleagues reported in 1995 their experience with 31 patients with longstanding primary hypothyroidism considered stable on levothyroxine for at least 6 weeks prior to entering their protocol. Most of these patients were being treated with Synthroid and they were switched to a Levoxine preparation and 8 were treated with Levoxine and then switched to Synthroid.
This slide demonstrates the Synthroid TSH values on the left and the Levoxine TSH values on the right which is the primary illustration from the publication. What that illustration actually obscures is the fact that 6 out of 24, or 24 percent, of those that were considered euthyroid while on Synthroid were then