The anabolic effects of parathyroid hormone

Several generations ago, the catabolic effects of parathyroid hormone (PTH) on the skeleton gave rise to the description of primary hyperparathyroidism as a disease of `bones, stones and groans'. The skeleton is still universally affected in severe primary hyperparathyroidism. Classical radiographic features include degranulation of the skull (so-called salt and pepper appearance), distal tapering of the clavicles, subperiosteal bone resorption of the phalanges, brown tumors and bone cysts. Both cancellous and cortical elements of the skeleton are affected with the spine (primarily cancellous bone) and the distal radius (primarily cortical bone) showing such catabolic consequences. It is this classic presentation of primary hyperparathyroidism that has given rise to the idea that PTH is bad for bones. In this review we will summarize information from an increasingly compelling set of animal and human data indicating that under certain circumstances, PTH is good for bones.