EFFECT OF TREATMENT OF HYPOTHYROIDISM ON CIRCULATORY RESPONSE TO ADRENALINE

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Abstract
The response of the pulse rate and isometric period of cardiac contraction to graded doses of intravenous epinephrine was determined in 3 hypothyroid patients before and after treatment with the thyroxin isomers. Treatment did not appear to increase the cardiovascular sensitivity to epinephrine except in one patient treated to the stage of hyperthyroidism, suggesting that the synergism between thyroid hormone and the catecholamines may exist only at abnormally high levels of thyroid hormone activity. The response to intravenous epinephrine was similar in a patient when maintained euthyroid by dextro- and by levo-thyroxin in succession. The circulatory response to insulin-induced hypoglycaemia was increased by the correction of hypothyroidism, probably as a result of increased epinephrine secretion from the adrenal medulla.