Effect of thyroid hormones on osteolysis "in vitro".

The effect of triiodothyronine and thyroxine no the stimulation of the release of 45Ca was followed up in rat calvaria incubated "in vitro" and compared with the effect produced by parathormone. Both triiodothyronine and thyroxine stimulated osteolysis. The response was dependent on dose. Triiodothyronine may intensify the effect of parathormone if added to the incubation medium, whereas thyroxine does not exert the same effect. The results obtained demonstrated a well defined osteolytic effect of both thyroid hormones.