Effect of Thyroparathyroidectomy on the Action of Irradiated Ergosterol.

In a recent publication 1 we suggested that irradiated ergosterol increased the calcium concentration of the blood by acting on the parathyroid glands. This view was based on the following observation: Latent tetany, manifested by calcium concentration of about 6 mg. per 100 cc. of serum, was first brought about in a monkey by means of a low calcium diet. It was then found possible to raise the calcium level to about 11 mg. by means of large amounts of irradiated ergosterol given by mouth. However, after extirpation of the parathyroid glands, the calcium could not be elevated much above 7 mg. per 100 cc. of serum. Slight hypercalcemia was induced by means of injections of parathyroid extract (Collip).

Urechia and Popoviciu 2 have given irradiated ergosterol to dogs in which tetany had been induced by means of parathyroidectomy. They concluded that the tetany was not relieved by this means nor the calcium level raised. They do not state the exact composition of the dietary. Brougher 3 carried out similar experiments. He concluded that irradiated ergosterol “when given in conjunction with milk from the day of operation prevents the development of violent tetany.”

During the past year we have carried out numerous extirpation experiments on monkeys and on dogs with the same object in view. In many instances the technic has been modified by giving irradiated ergosterol at the outset in order to establish the fact that hypercalcemia could be induced; levels of 13-16 mg. per 100 cc. of serum were brought about in this way. Following operation, however, we were not able to raise the calcium above the normal level. It should be added that after large doses of irradiated ergosterol has been given for a period of some weeks, removal of the parathyroid glands does not result in the precipitous fall in the calcium which we are accustomed to observe following extirpation.