A 5-YEAR CONTROLLED RANDOMIZED STUDY OF PREVENTION OF POSTMENOPAUSAL TRABECULAR BONE LOSS WITH NASAL SALMON-CALCITONIN AND CALCIUM

The aim of this paper was to evaluate the long-term (5 years) efficacy of nasal salmon calcitonin in prevention of trabecular postmenopausal bone loss, which was a follow-up of a previously published study (3 y ears); a randomized, controlled group comparison. One hundred healthy postmenopausal women were randomly chosen from those (186) having comp leted the 3 year protocol. The 100 women were allocated to an addition al 2 year period (total of 5 years) of treatment with either 500 mg d( -1), 5 days week(-1) of calcium or the same amount of calcium plus 50 IU d(-1), 5 days per week of nasal salmon calcitonin, 87 (87%) women c omplied with the protocol throughout. The main outcome measures were t he bone mineral density of the lumbar spine (1-BMD) (DPA) and biochemi cal parameters reflecting bone turnover (serum alkaline phosphatases, urinary calcium/creatinine and hydroxyproline/creatinine ratios). The women receiving calcium alone presented a significant decrease in 1-BM D after 6 months [-1.6 (0 5)%] [mean(SEM)] (P<0.01) and this decrease remained significant after 36 months [-6.1(08)%] (P<0.01) and until th e end of the trial [-6.6(10)% at t60] (P<0.01). In women receiving cal cium and calcitenin, 1-BMD significantly increased after 36 months [+2 (0. 7%] (P<0.01) and 42 months [+2.5(0.7)%] (P<0.01) and was unchanged at the other times of investigation [+1.1(1.1)% at t60] (NS). The evo lution of BMD in the two groups was highly significantly different (P< 0.001) since the sixth month of the study and remained so until the en d of the study. No differences were observed in the biochemical parame ters reflecting bone turnover. Nasal administration of salmon calciton in, using a low-dose (50 IU d(-1)), intermittent (5 days week(-1)) reg imen, may totally prevent postmenopausal bone loss, at the level of th e lumbar spine, for at least 5 years, if the treatment is continued fo r this duration. It is not clear whether the results observed during t he fourth and fifth years are fully attributable to calcitonin or if c alcium by itself plays also a protective role against trabecular bone loss.