Abstract

The influence of the thyroid state on hemodynamic responses to i.v. infusions of graded doses of norepinephrine and epinephrine was studied in five patients with spontaneous hyperthyroidism. Each patient was studied during a hyperthyroid session and again several months after treatment with radioactive iodine during a euthyroid session. The average increments in systolic, mean and diastolic arterial pressures, mean right atrial pressure and total systemic resistance and the decrements in heart rate and cardiac index during infusions of graded doses of norepinephrine (0.075-0.30 µg/kg/min) in the hyperthyroid session were not significantly different from their responses when the patients were euthyroid. The increments in systolic, mean and diastolic systemic arterial pressures, mean right atrial pressures, heart rate and cardiac index and the changes in total systemic resistance during infusions of graded doses of epinephrine (0.075-0.30 µg/kg/min) also were not appreciably different in the two sessions. These findings indicate that the hyperthyroid patient, like the hypermetabolic subject or animal, does not exhibit augmented hemodynamic responses to norepinephrine and epinephrine.