On the assumption that, because the injection of parathyroid extract increases the calcium in the blood stream, there will be more available calcium for deposit in fracture callus, have been based certain clinical trials of parathyroid extract in the treatment of delayed union of fractures. The occurrence of union after the use of the hormone has confused the issue. It is our belief that parathyroid extract is being widely used on the misapprehension that it is of such value.
A priori, parathyroid extract should not offer aid in hastening or inducing the deposit of calcium in the soft callus about fractures. Its action is to mobilize the fixed calcium in the body. Indirect evidence of this action is presented by the work of several investigators including Hunter and Aub,1 who found that calcium excretion in patients is rapidly increased parallel to an increase in the blood serum calcium on