A NEW BIOCHEMICAL MARKER OF BONE-RESORPTION FOR FOLLOW-UP ON TREATMENT WITH NASAL SALMON-CALCITONIN

In a double-blind, placebo-controlled, randomized group comparison, ne w and specific biochemical markers for bone resorption as follow-up pa rameters on the therapeutic response to nasal salmon calcitonin (sCT) were evaluated. Evaluation took place at an outpatient clinic where os teoporosis was being researched. The subjects included 208 women aged 68-72 treated for 2 years with either 50 IU, 100 IU, or 200 IU of nasa l sCT or placebo; all groups received a daily calcium supplementation of 500 mg. Only 164 women fulfilled the study as valid completers. Mar kers were applied to frozen urine samples of a previously published in tervention study of a new fasting urinary (fU) biochemical marker for bone resorption (CrossLaps(TM), ELISA) and the urinary excretion of cr oss-links (pyridinoline and deoxypyridinoline) was measured, all corre cted for creatinine. Bone mineral density of the lumbar spine and rate s of vertebral and peripheral fractures were measured after 2 years of treatment. The creatinine corrected urinary pyridinoline, deoxypyridi noline, and CrossLaps showed maximum decreases of 10-43% (95% confiden ce interval -29.5% to 9.6% and -75.1% to 9.3%; P < 0.01-0.001) after 6 -9 months, after which the response leveled off. A significant differe nce among the four treatment groups was seen in fU CrossLaps (P < 0.01 ). The changes in spinal bone mass were significantly related to the d ecreases in fU CrossLaps: women with the highest response in spinal bo ne mass had decreases in fU CrossLaps of 44% (-83.5% to 7.4%) and wome n without response of 5% (-57.6% to 99.9%) P < 0.001). In women who fr actured during the 2-year period, fU CrossLaps remained unchanged, whe reas decreases of 30% (-75.1% to 44.7%) were seen in women who did not fracture (P = 0.002). The results suggest that biochemical markers ca n be used to determine the optimum treatment regimen of nasal sCT. The response of the new marker, fU CrossLaps, significantly reflects the responses in bone mass of the spine and fracture rates.