The effects of dopamine, dopexamine and dobutamine on TSH secretion in healthy subjects

Objective: To compare the effects of three catecholamines on thyroid stimulating hormone (TSH) secretion. Dopamine is known to inhibit TSH secretion from the anterior pituitary in man, but the effects of dopexamine and dobutamine have not been studied. Design: A randomized, placebo controlled, double-blind crossover study on eight healthy, male volunteers. On four separate occasions subjects were given an infusion of either dopamine or dopexamine or dobutamine or placebo (0.9% saline). The study took place during the evening so that the evening increase in TSH would be seen. Infusions were titrated to the same cardiovascular end-points and kept within the ranges of 2.5-10 μg/kg/min dopamine, 5-20 μg/ kg/min dobutamine and 1-4 μg/kg/min dopexamine. Setting: Teaching hospital. Subjects: Eight healthy male volunteers who had given informed consent. Results: Infusion of dopamine caused a decrease in TSH concentration (p<0.05) compared to 0.9% saline, dobutamine or dopexamine. TSH remained suppressed until ...