Skeletal effects of cyclic recombinant human growth hormone and salmon calcitonin in osteopenic postmenopausal women.

Abstract

The objectives of this study were to determine whether cyclic administration of recombinant human GH, with or without the antiresorptive agent, salmon calcitonin (CT), provides clinically meaningful increases in bone mineral density (BMD) at the lumbar spine and proximal femur in postmenopausal osteopenic women. The design of the study was a randomized clinical trial consisting of 12 56-day treatment cycles. Each cycle was initiated by a 12-day period of hormone administration, followed by 44 days of supplemental calcium only. Cycles of hormone administration consisted of 7 daily injections of recombinant GH (20 micrograms/kg.day) or its placebo, followed by 5 daily injections of salmon CT (100 U/day) or its placebo. The study was performed at the Palo Alto Veterans Affairs medical center. The patients were 84 healthy women with lumbar spine BMD more than 1 SD below the average value for a healthy 25-yr-old Caucasian woman. BMD was measured at the lumbar spine and proximal femur by dual energy x-ray absorptiometry. Biochemical markers of bone turnover and circulating insulin-like growth factor I were also measured. GH treatment increased insulin-like growth factor I concentrations from low values at baseline (112 +/- 56 ng/mL) to the young normal range (approximately 430 +/- 125 ng/mL). Groups receiving GH plus CT or GH plus placebo increased lumbar spine BMD at 2 yr by 2.70 +/- 0.81% (P < 0.01) and 1.72 +/- 0.74% (P < 0.05; intention to treat analysis). No significant change occurred in women receiving placebo plus CT or combined placebo. Significant increases in total hip BMD of 1-2% were observed for the GH plus placebo and placebo plus CT groups, with a nonsignificant trend in the GH plus CT group. For the femoral trochanter, significant increases were observed in the GH plus CT and placebo plus CT groups only. No significant change in femoral neck BMD was observed in any group. Women taking replacement estrogen had the same BMD response as those who were estrogen deficient. No significant increase in BMD was observed between 24 and 36 months in the 62 women who returned for a 3 yr measurement. In response to GH, short term increases in resorption and formation markers were observed, but these had decreased before the next treatment cycle. No long term changes in resorption markers were observed, but women in the GH groups showed a sustained rise in circulating osteocalcin over the entire 2-yr protocol. GH given cyclically with or without CT for 2 yr achieved statistically significant increases in BMD of the lumbar spine and selected areas of the hip in postmenopausal women. These gains were less marked than those achieved with estrogen or bisphosphonates and were associated with a relatively high incidence of adverse experiences. Therefore, it is unlikely that cyclic GH with or without CT will prove clinically useful in the treatment of postmenopausal women with osteoporosis.