This chapter in a book shows quite clearly that in the intact thyroid, T4 and T3 are tightly bound on to a protein called thyroglobulin. Only when this emerges from the thyroid is the T4 and T3 released as such. This has profound implications for NDT use, by mouth. This is because the T4 and T3 will not be immediately available to being absorbed until the protein has been digested in the stomach and small intestine and the hormones released. Therefore the implication is that as regards controlled uptake of the hormones, especially for T3, there won't be the kind of FT3 "spikes" that occur when T3 alone is taken. This may explain the benefits of NDT (DTE) as a slow release application if someone is sensitive to T3 spiking. It supports the use of NDT and downplays the strength of the argument that the ratios of T4 and T3 are different from humans.
“Thyroglobulin Storage, Processing and Degradation for Thyroid Hormone Liberation”: A Comprehensive Guide for the Clinician
January 2019
DOI: 10.1007/978-3-319-72102-6_3
In book: The Thyroid and Its Diseases
Klaudia Brix, Maria Qatato, Joanna Szumska, Maren Rehders