Estimation of the effect of salmon calcitonin in established osteoporosis by biochemical bone markers.

We reviewed data on 42 postmenopausal women with established osteoporosis (forearm fracture or a low bone mass) who had been randomly treated for 1 year with either rectal salmon calcitonin (sCT), 100 IU daily (n = 25) or nasal sCT, 200 IU daily (n = 17) applying an estimation algorithm for bone loss rates. Both groups received a daily calcium supplement of 500 mg. A group of 18 age-matched women who received no treatment served as controls. The bone mineral content of the distal forearm (BMCarm) was measured every 3 months by single photon absorptiometry. The individual rates of change during the 1-year period were calculated by linear regression analysis (alpha BMCarm). Bone loss rates were estimated initially and after 1 year of therapy by measurements of serum alkaline phosphatase, plasma bone Gla protein, and fasting urinary hydroxyproline and calcium (both corrected for creatinine excretion) according to the estimation algorithm. Both administration forms revealed significant control group-corrected decreases in serum and urine markers of bone turnover of 15-40% (P < 0.05-0.01) and positive outcomes of 2% in alpha BMCarm (P < 0.01). The estimated effect on bone mass was expressed as the difference between the bone loss estimated after 1 year and initially (delta ESTBIO). A significant correlation was seen between alpha BMCarm and delta ESTBIO (r = 0.5, P < 0.0001). We conclude that the effect of sCT on bone can be followed up by biochemical markers for bone turnover, i.e., by an annual blood and fasting urine sample, applying an estimation algorithm for the rate of bone loss.