Parathormone in the Treatment of Osteoporosis

Overview

In the submitted review the author discusses the anabolic effect of intermittently administeredparathormone on bone which is a new alternative in the treatment of osteoporosis. While permanentexposure to parathormone leads to hyperparathyroidism associated with bone resorption and lossof bone mass, intermittent administration of parathormone (i.e. once per day) induces paradoxicallyincreased mineralization of bone trabeculae,endostealandperiosteal surfaces. As an anabolic factorPTH (parathormone) has a much greater therapeutic potential than antiresorptive substances.Stimulation of bone formation by rhPTH 1-34 (recombinant human parathormone) was proved,which leads to greater firmness of bone and reduces the frequency of fractures.Recombinanthumanparathormone (1-34) (rhPTH(1-34)) administered once per day increases the BMD and reduces thefrequency of fractures in the area of vertebral bodies. RhPTH 1-34 enhances lamellar bone appositioneven at a lower bone turnover. An increase was proved in the region of trabecular and corticalbone without an increase of porosity of cortical bone and also an incresed connectivity of osseoustrabeculae was proved which means thatPTHleads to an increase of bone quantity aswell as quality.PTH has an anabolic effect on cortical bone as well as on trabeculae. From studies, quoted in thepaper an increase of bone density (BMD) in the spinal region during PTH therapy is apparent inmen and women. This increase in BMD values is clearly higher than the observed increase of BMDin antiresorptive treatment. Bone markers indicate an increase of values of proformative markerswhich is followed by an increase of proresorption markers. In the course of time markers of the boneturnover have a tendency to return to baseline values while another increase of BMD is under way.PTH can be used for the treatment of men with primary osteoporosis. PTH leads to a dramaticincrease of bone mass in the area of the lumbar spine and hip joint also in postmenopausal womenwith glucocorticoid-induced osteoporosis. Clear evidence was provided of an association betweenPTH treatment and a reduced incidence of fractures. The author mentions also studies with PTHtreatment; their results are presented and commented.

Key words:
osteoporosis, parathormone