A DETERMINATION OF THE RATE OF THYROID HORMONE SECRETION AT VARIOUS ENVIRONMENTAL TEMPERATURES¹

Abstract

THERE ARE many observations which suggest that the thyroid secretesits active principle more rapidly in cold than in warm environments. For example, physiological investigations have demonstrated increased metabolic rates after exposure to cold (Ring, 1939) and decreased rates after exposure to heat (MacGregor and Loh, 1941). Similarly, histological evidence of stimulation may be seen in thyroids removed from rats maintained in cold environments, while evidence of diminished secretion is apparent in glands of rats kept at high temperatures (Cramer, 192,8). Moreover, it has been pointed out that hyperthyroid crisis is a more common clinical occurrence in geographical regions where the temperature shows wide fluctuations than in areas with a more gentle climate (Petersen, 1937). As these observations are based on diverse criteria and are in agreement that the thyroid gland is stimulated by cold, this conclusion may be accepted with considerable confidence.