Studies on the Mode of Action of Irradiated Ergosterol

The hypothesis has been advanced that irradiated ergosterol acts only by stimulating the parathyroid glands (1-3). Yet various workers have reported beneficial results in the treatment of parathyroid deficiency with irradiated ergosterol (1), ( It is difficult to believe that if irradiated ergosterol acts by stimulating the parathyroid glands, its administration to completely parathyroidectomized animals should result in alleviation of the tetany and restoration of the serum calcium and phos- phorus to normal values. The lack of complete calcium and phosphorus metabolism data, failure to state the dietary intake, and variations in dosage as well as differences in potency of the irradiated ergosterol prepa- rations employed, make it difficult to draw any conclusions from the work reported in the literature as to the mode of action of irradiated ergosterol in parathyroid tetany. The results obtained in certain instances may very well have been due to overdosage of this potent vitamin D prepara- tion (8).