In recent years a number of workers have used various methods of acid extraction to isolate from fresh parathyroid glands a substance, which, when given parenterally in adequate doses, produces a remarkable rise in the concentration of calcium in the blood serum. Collip and his associates have shown that the injection of a potent extract raised the concentration of serum calcium not only in parathyroidectomized dogs in whom the initial values were low, but also in intact dogs in whom the initial values were normal. Collip1 has recently published a comprehensive review of this experimental work.
A few observers2 have used such extracts, the potency of which had been proved in animals, in the treatment of both idiopathic and accidentally induced tetany in man. In all the reported cases the patients were relieved of clinical symptoms during the period of administration. Analyses of the blood showed that an