[Parathyroid and bone. Effects of parathyroid hormone on bone resorption and formation: differences between intermittent and continuous treatment].

The continuous treatment with parathyroid hormone (PTH) or endogenous PTH excess by primary hyperparathyroidism cause enhanced bone resorption and subsequent decreased bone volume. However, the intermittent treatment with PTH is expected as a drug for osteoporosis for its stimulation of bone formation and marked increase in bone volume. The mechanism of different PTH actions due to the administration method still remains unclear. Several reports suggested the hypothesis about the role of insulin-like growth factor-1, anti-apoptotic effects through Runx2 or Smad3 and the differences of its effects on bone resorption. The investigation about the mechanism of bone formation by PTH intermittent treatment would lead to the development of bone-forming reagent in the future.