The Effect of Oral Alendronate and Intranasal Calcitonin on Bone Turnover and Bone Mineral Density in Postmenopausal Osteoporosis.The aim of this study was to compare the effects of alendronate (ALN) and salmon calcitonin (sCt) on the biochemical markers of bone turnover and bone mineral density (BMD) in postmenopausal osteoporosis. Seventy six postmenopausal women with osteoporosis aged between 44-74 years were included in this study. The patients in the first group received daily doses of 10 mg ALN and the patients in the second group used intranasal sCt at a dosage of 100 IU/day. All patients also received daily doses of 500 mg calcium supplements. Serum Ca, P, ALP and urinary deoxypyridinoline (Dypr), spot urinary calcium and 24 hour urinary calcium measurements were done at baseline and at the sixth month of the treatment. DXA was used for the measurement of BMD of the lumbar spine and proximal femur. At the end of the six month ALN treatment produced marked decrease in Dypr (p<0.001) and a significant increase in BMD at the lumbar spine (p<0.001) and in all regions at proximal femur (p<0.001). In contrast, intranasal sCt failed to increase BMD in proximal femur (p>0.05) and no significant change was observed in urinary F-Dypr levels (p>0.05), but there was a significant increase in BMD of the lumbar spine (p<0.001). These results showed that ALN treatment decreased bone turnover and increased BMD in postmenopausal women with osteoporosis. Although intranasal sCt made an increasement in BMD at lumbar spine, it seemed ineffective to reduce bone turnover at a dosage of 100 IU/day. In conclusion, ALN appears to be a suitable choice in the treatment of postmenopausal osteoporosis. We suggest that higher doses of intranasal sCt may have greater effects on bone turnover and BMD.