This paper at present in preliminary abstract form investigates using T3-sulphate rather than T3 for combination therapy:
Front. Endocrinol. | doi: 10.3389/fendo.2019.00826
TREATMENT OF HYPOTHYROID PATIENTS WITH L-THYROXINE (L-T4) PLUS TRIIODOTHYRONINE SULFATE (T3S). A PHASE II, OPEN-LABEL, SINGLE CENTRE, PARALLEL GROUPS STUDY ON THERAPEUTIC EFFICACY AND TOLERABILITY
Ferruccio Santini1*, Giovanni Ceccarini1, Caterina Pelosini1, Monica Giannetti1, Ilaria Ricco1, Giorgia Querci1, Enzo Grossi2, Giorgio Saponati3 and Paolo Vitti1