Studies on the physiology of the parathyroids

Abstract

We possess at the present time no exact knowledge concerning the function of the parathyroids. There are many theories, but only three have gained some importance, namely that the parathyroids control (1) the guanidine metabolism and by doing so regulate the tonus of the muscles; (2) the calcium metabolism; (3) the acid-base equilibrium and their removal cause alkalosis. The parathyroids also are supposed to control the sugar metabolism to some extent.In the present work the changes in certain constituents of the blood have been studied following partial and complete parathyroidectomy in dogs, care being taken to leave enough thyroid tissue to prevent cachexia. Partial extirpation was done in 7 dogs, complete removal in 10 dogs.I. Partial Parathyroidectomy. Three glands were removed. In no case did the animals show any symptoms of tetany, and apart from a little depression and loss of appetite the first few days showed no symptoms at all. In 6 of these dogs the fourth gland was removed later.The blood sugar was absolutely unchanged. The alkali reserve usually was lowered the first few days after the operation; corresponding to this lowered alkali reserve there was an increase of acid elimination. The serum calcium decreased from a normal value of 10.0 mg. to a minimum of 7 mg. per 100 c.c.In 2 of the 7 dogs there was no decrease in calcium; microscopic examination showed that only two parathyroids were taken out; in one of these dogs the third parathyroid was removed some time afterwards and the calcium dropped down to about 8 mg. Within two weeks the calcium was restored again to the normal. As a control a normal dog was given the same anesthetics used in the operations (chloroform and ether, equal parts); the alkali reserve dropped considerably, but the calcium remained unchanged.