Effectiveness of parathyroid hormone, calcitonin and phosphate on bone cells in Paget's disease

In two patients with primary hyperparathyroidism and Paget's disease, measurement of biochemical variables and quantitative histology showed that calcitonin plus oral phosphate therapy induced a dramatic decrease in serum calcium and in osteoclast count and osteoclastic surface in bone, contrasting with a substantial increase in serum phosphate and in osteoblastic surface in bone. Removal of the adenomas was followed by a two- to threefold increase in the osteoblastic surface. In one patient in whom only the right ilium was pagetic, biopsy specimens obtained from both iliums revealed that calcitonin plus phosphate therapy had a greater effect on the pagetic bone cells and that adenomectomy (A-PTX) had a greater effect on the normal bone cells. In addition the increased number of nuclei per osteoclast in the pagetic bone decreased after calcitonin plus phosphate therapy but remained unchanged after A-PTX. A positive correlation was found between the size of the preexisting pool of osteoclast nuclei and the appearance of osteoblasts after calcitonin administration or PTH suppression, suggesting that the osteoclasts are the immediate precursors of the osteoblasts.