Studies in thyroid activity. II. The Specific Physiological Activity of Certain Constituents of the Thyroid Gland

Investigations of the physiological activity of the thyroid gland have shown that the internal secretion of the gland serves many different functions. One or more of a series of symptoms accompany cases of thyroid deficiency. These symptoms are relieved by the administration of the thyroid gland of certain animals, as the sheep, hog, and ox. When this treatment is stopped the symptoms return. It would thus appear that the functions of the internal secretion of the thyroid may be fulfilled by furnishing the body with the constituents of the thyroid gland from another animal. The separation of the various chemical constituents briefly described above suggested the possibility of determining which constituents controlled the various symptoms occurring in cases of thyroid deficiency. The first step in the method of separation of the constituents results in two solutions. One of these contains about 60 per cent. of the total iodine and 9 per cent. of the nitrogen. This is designated “Solution A.” The other, called “Solution B,” contains 40 per cent. of the total iodine and 91 per cent. of the nitrogen. In order to establish the physiological activity of these solutions, experiments were carried out, first upon dogs, and then with cases of thyroid deficiency. The number of cases treated is insufficient to establish completely the physiological properties of these solutions, but the results based upon a series of experiments with two dogs extending over four months, with two typical cases of myxedema, and with three cretins, are as follows: Solution A was found: (1) to affect the nitrogen metabolism and hence the body weight and temperature; (2) to produce tachycardia; (3) to cause nervousness and tremor; (4) to relieve pain and great weakness felt in the back and certain sensations of cold felt on the head.