Treatment of osteoporosis with recombinant parathyroid hormone, utilisation of total body DXA to observe treatment effects on total body composition and factors determining response to therapy.

Recombinant parathyroid hormone (rPTH) increases bone mineral density (BMD). However, certain other potential effects of rPTH remain to be studied. The aim of this study is to identify whether bone turnover markers, relevant biochemical parameters or total body fat and muscle composition affect the response to rPTH and to establish if these parameters in particular change during treatment. One hundred seventy-two participants were treated with rPTH, and 128 subjects who fully complied with the therapy and completed their investigations including biochemical bone markers and total body composition at baseline, 6 months and 1 year of the treatment were divided into responder and non-responder groups. A total body dual-energy X-ray absorptiometry (DXA) scanner was used to assess the body muscle, fat and bone composition. rPTH significantly increased BMD spine at 1 year (p = 0.000). Twenty-four-hour urinary calcium was significantly increased at 6 months in the responder group (p = 0.00). There was a trend to an increase in the fat and muscle mass (p = 0.52 and 0.45, respectively), and it was not negatively affected by rPTH. Bone turnover markers (P1NP and OC) did not show statistically significant difference over time between responders and non-responders (p = 0.74 and p = 0.19, respectively). Hypercalciuria which is a frequent feature in osteoporotic population may predict non-responders at 6 months of rPTH, and it may help to optimise individual patient's treatment. Unlike endogenous PTH in pathological conditions, rPTH is anabolic to bone and has no detrimental effects on the body fat and muscle composition.