Abstract
The preponderance of experimental data on specific dynamic action of food in thyroid diseases, reported during the last decade by six investigators from as many laboratories, indicates that there is no change from the normal (DuBois, 1 Aub and Means, 2 Undeutsch, 3 Rolly, 4 Plaut, 5 and Liebesny. 6 ) Weiss and Adler, 7 however, found an increased specific dynamic action in one case of Graves' disease, while in one case of myxedema it was also increased.
One never finds surviving cases of myxedema in infants or adults without active thyroid tissue. In Graves' disease thyroid activity while usually greater than normal, may be normal or subnormal. Since clinical conditions obtaining in thyroid diseases are so complex and variable, it seemed worth while to study the relation of thyroid to specific dynamic action of food under conditions more simplified and limited.
If the thyroid, and hence probably its secretion, were necessary for specific dynamic action to manifest itself then no specific dynamic action should result in completely thyroidectomized animals. If the thyroid gland is not a factor in this phenomenon, then there should not be much difference in the specific dynamic action before and after thyroidectomy.
Rabbits were chosen for the experimental animal because their thyroids can be completely removed without interfering with the inferior parathyroid glands. The greatest disadvantage of using an herbivorous animal for metabolism experiments in which a basal level is at times desired, lies in the fact that it is difficult to empty completely their alimentary canals, even after a four day fast, and yet have the animal otherwise in a physiological condition. By starving rabbits 36 to 48 hours their R Q's were usually below 74 which we regarded as satisfactory for our purpose.
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