Abstract
In a recent note 1 we reported that calcium in the blood could be raised to abnormal levels in dogs and in monkeys by feeding large amounts of irradiated ergosterol, but that hypercalcemia could not be induced by this means after the parathyroids and thyroids had been extirpated. In these experiments, the amount of ergosterol which was given was usually about 40 times that which is prescribed for infants of equivalent weight.
In the course of subsequent experiments of this kind, we have found that if still larger amounts of irradiated ergosterol are given, it is possible to induce hypercalcemia, after the thyroid and parathyroid glands have been excised. For this series of tests, 100 to 400 times the therapeutic dose has been given; in some instances as much as 800 times this dosage has been fed. Under such conditions, the calcium may rise from 6 or 7 mg. to 17 or even 20 mg. per 100 cc. of blood. That the parathyroids had been completely removed from the body, was shown furthermore by the fact that the inorganic phosphorus in the urine became markedly decreased or even was entirely absent following the operation.
As stated previously 2 we are of the opinion that the source of the marked increase in serum calcium induced by excessive amounts of irradiated ergosterol is the tissues, more particularly the bones, which are the great storehouses of calcium in the body. Subsequent investigations have confirmed this point of view. If dogs are fed, for a period of weeks or even months, on a diet which is almost free of calcium, being composed of cracker meal, dried meat and mazola (corn) oil, the calcium of the blood can be raised to abnormal levels by feeding excessive amounts of irradiated ergosterol, in spite of the deficiency of calcium in the ration.
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