Basal plasma levels of calcitonin and bone mineral mass in normal and uremic women. Effect of menopause.

Basal plasma levels of immunoreactive calcitonin (iCT), forearm bone mineral content (BMC) as measured by 125I photon absorptiometry and 24-hour urinary hydroxyproline/creatinine ratio (OHPr/Cr) were determined in 32 healthy women (13 pre-menopausal, aged 40 to 54 years, and 19 post-menopausal, aged 41 to 54 years). The basal plasma levels of iCT were significantly higher in the pre-menopausal group (mean value 96 vs 54 pg/ml, P less than 0.025). The BMC value of the radius was also significantly greater in the same group (mean +/- SEM 656 +/- 13 vs. 620 +/- 9 mg/cm2, P less than 0.05), while the urinary OHPr/Cr ratio was higher in the post-menopausal group (29.9 +/- 1.5 vs. 38.7 +/- 2.7 mg/g, P less than 0.02). These results suggest that basal plasma levels of iCT decrease after the menopause and support the hypothesis that a deficiency of CT could be involved in the pathogenesis of post-menopausal bone loss. Similar results were obtained in 25 uremic women on maintenance hemodialysis (9 pre-menopausal and 16 post-menopausal) aged 30 to 65 yrs.: both basal iCT levels and BMC values were significantly higher in the pre-menopausal group.