The evolution of the concept of hyperparathyroidism may be traced in successive stages from the original description of osteitis fibrosa cystica by von Recklinghausen1 to its emergence as a disorder of function of the parathyroid glands, culminating in Mandl's2 important observation that removal of a parathyroid adenoma resulted in marked immediate clinical improvement of the condition. The chain of evidence at present is almost complete that excessive secretion of parathyroid hormone by such an adenoma is to be regarded as the essential cause of the bony changes, hypercalcemia, and associated phenomena of this disease.3 Reports in the available literature, however, contain no instances in which the actual hormone content of adenomas removed surgically has been determined.
Removal of a parathyroid adenoma in the following case permitted a biologic assay of its hormone content:
REPORT OF CASE
—A woman, aged 42, was admitted to