Bone mass continues to increase at the hip after parathyroid hormone treatment is discontinued in glucocorticoid-induced osteoporosis: Results of a randomized controlled clinical trial

Glucocorticoid-induced osteoporosis is the most common secondary cause of o steoporosis. In this 24-month study, we report changes in bone turnover and bone mass after 12 months of daily injections of human parathyroid hormone 1-34 [hPTH(1-34)] and 12 months off treatment in postmenopausal women (mea n age, 63 years) with osteoporosis treated with glucocorticoid and hormone replacement therapy. Response to the treatment was assessed with bone miner al density (BMD) measurements of the lumbar spine by quantitative computed tomography (QCT); BMD measurements of the lumbar spinel hip, and forearm by dual-energy X-ray absorptiometry (DXA); and biochemical markers of bone tu rnover. The mean (+/-SEM) change in BMD of the lumbar spine by QCT and DXA in the PTH group at 24 months was 45.9 +/- 6.4% and 12.6 +/- 2.2% (p < 0.00 1). The change in total hip and femoral neck BMD was not significant at 12 months but increased to 4.7 +/- 0.9% (p < 0.01) and 5.2 +/- 1.3% at 24 mont hs, respectively, as compared with a relatively small change of 1.3 +/- 0.9 % and 2.6 +/- 1.7% in the estrogen-only group. The mean percent differences in BMD of the lumbar spine by QCT and DXA between the groups at 24 months were 43.1% and 11.9%, respectively (p < 0.001), The mean percent difference s over the estrogen-only group in hip BMD were 3.4% for total hip (p < 0.01 ) and 2.6% for femoral neck at 24 months. Biochemical markers of bone turno ver increased to more than 150% during the first 6 months of therapy, remai ned elevated throughout the 12-month treatment period, and returned to base line values within 6 months of discontinuing the PTH treatment. These resul ts suggest that PTH dramatically increases bone mass in the lumbar spine an d hip in postmenopausal women with glucocorticoid-induced osteoporosis who are taking hormone replacement therapy, However, the maximum effect of this anabolic agent on bone mass at the hip after 12 months of treatment requir es at least 6-12 months after the PTH treatment is discontinued.