Effects of Low Dose Oral Triiodothyronine in Myxoedema Coma

Some of the immediate cardiovascular changes and alterations in oxygenation occurring in a patient in myxoedema coma following the oral administration of a single dose of triiodothyronine (T3) (2.5 micrograms) are described. These included increases in oxygen consumption, oxygen delivery, cardiac output, heart rate and ventricular stroke work. Low dose oral T3 can be effective in myxoedema coma and these patients may benefit from the continuous, comprehensive monitoring which can be provided in an intensive care unit. Our observations suggest that over-vigorous attempts to reverse the hypothyroid state could precipitate tissue hypoxia and/or myocardial ischaemia.