To the Editor.—
Retrospective analysis of reported cases of myxedema coma leads to the conclusion that vigorous therapy with thyroid hormones favors survival. To derive optimum dosage schedules, our approach, patterned after that of Holvey et al,1 has been to estimate how much hormone would be needed to bring body hormone stores and plasma levels to normal, and then give somewhat less than this estimated total replacement.2 Compared to this approach, Newmark et al (230:884, 1974) recommend doses of liothyronine sodium (50μg initially, then 25μg every eight hours) that are too large and doses of levothyroxine sodium (200μg intravenously or 250μg orally initially, then 50μg intravenously or 75μg orally every eight hours) that are too small.
Treatment With Liothyronine.—
The extrathyroidal pool of triiodothyronine (T3) in normal individuals is about 50μg. Thus, an initial dose of 50μg of liothyronine sodium would provide sudden total replacement, leading to