Calcitriol corrects deficient calcitonin secretion in the vitamin D-deficient elderly

Effects of the combined use of calcitonin and 1 alpha-hydroxycholecalciferol on vertebral bone loss and bone turnover in women with postmenopausal osteopenia and osteoporosis: a prospective study of long-term and continuous administration with low dose calcitonin

OBJECTIVES

The present study investigates the effect of long-term and continuous treatment with low dose calcitonin in combination with 1 alpha-hydroxycholecalciferol on vertebral bone mass in early postmenopausal women.

METHODS

A total of 202 postmenopausal women between 53 and 58 years of age were recruited individually and randomly assigned to one of four groups. Comparisons were made among groups of women receiving calcitonin alone (10 IU i.m. twice a month), 1 alpha-hydroxycholecalciferol alone (0.5 microg orally twice daily), a combination of the above two agents, or no treatment. Bone mineral density (BMD) of lumber spine (L2-4) was determined using Dual Energy X-ray Absorptiometry. The study was carried out prospectively over a 2-year period.

RESULTS

We observed a significant increase in vertebral bone mass in the combined treatment regimen of calcitonin and 1 alpha-hydroxycholecalciferol (3.44% at 12 months in the combination group vs 1.40,0.92, and -0.70% in the calcitonin alone, 1 alpha-hydroxycholecalciferol alone, and control groups, respectively; 4.51% at 24 months in the combination group vs 2.21,1.04, and -3.61% in the calcitonin alone, 1 alpha-hydroxycholecalciferol alone, and control groups, respectively). Serum PTH, osteocalcin levels and alkaline phosphatase activity decreased significantly within 12 months whereas urinary pyridinoline/creatinine ratio decreased at 24 months in the combination group. We observed mild adverse effects in 25.0% (7/28) and 30.0% (6/20) of combination regimen and calcitonin treatment cases, respectively.

CONCLUSIONS

The results of the study suggest that the combination treatment regimen increased vertebral bone loss in early postmenopausal women to a greater extent than did calcitonin alone or 1 alpha-hydroxycholecalciferol alone.

Calcitonin reserve in different stages of atrophic autoimmune thyroiditis

The objective of this study was to determine the calcitonin (CT) hormone reserve in different severity of atrophic autoimmune thyroiditis (AAT). Forty-eight female patients with AAT were divided into four groups based on basal and peak thyrotropin (TSH) values (after oral thyrotropin-releasing hormone [TRH], free triiodothyronine (FT3) and free thyroxine (FT4) ranging from normal in group 1 to overt hypothyroidism in group 4. All had thyroid antibodies. The control group comprised euthyroid females of comparable age, without thyroid antibodies. Basal CT and CT response to calcium infusion (area under the curve) were investigated as parameters of CT reserve. Basal CT was lower in groups 2 to 4 of patients with AAT (compared to controls), but the difference was not significant. Stimulated CT levels were lower (p < 0.05) in all groups of patients compared to controls, with markedly reduced CT-secretory reserve in group 4. Thyroid antibody concentrations and, basal and postinfusion calcium levels were not significantly different among the various groups. In conclusion CT deficiency (especially stimulated values) occurs in AAT and is more severe in hypothyroid patients than in earlier stages of AAT.

Continuous cleanup/preconcentration procedure of hydroxyvitamin D3 metabolites in plasma as an alternative to batch solid-phase extraction

A continuous automatable cleanup procedure coupled on-line with a liquid chromatograph and UV detector for hydroxyvitamin D3 metabolites [24,25-(OH)2, 1,25-(OH)2 and 25-(OH)] as an alternative to batch solid-phase extraction is reported. The method, based on continuous solid-phase cleanup/preconcentration of the analytes, requires only the passage of the sample through a single minicolumn, which also results in a preconcentration effect which increases the sensitivity. The proposed method is also compared with a conventional batch, two-step solid-phase extraction method previously improved by the authors. The method has been checked by applying it to plasma samples spiked with the target analytes (linear range between 0.05 and 100 ng/ml with coefficient of variation values lower than 6.5%) and acceptable recoveries ranging between 94.6 and 101% have been obtained. The sampling frequency was 4 h-1.

1-alpha-Hydroxyvitamin D3 treatment decreases bone turnover and modulates calcium-regulating hormones in early postmenopausal women

50 Japanese women within 10 years after menopause (mean age 52.5 years) were studied to determine the effects of 0.75 microgram of 1-alpha-hydroxyvitamin D3 [1-alpha-(OH)D3] with calcium (150 mg/day) (treated group: N = 25) and calcium only (control group: N = 25) for 12 months on bone mass and metabolism. Their L2-4 BMD measurements were 1.5 SD below the mean value of Japanese young, normal women. L2-4 BMDs increased significantly in the treated group (+2.1%; p < 0.01), but decreased significantly in controls (-2.1%; p < 0.01). Although serum calcium and creatinine remained unchanged in both groups, phosphorus levels increased significantly in the treated group (p < 0.01). Urinary calcium/creatinine (Cr) increased in both groups. Urinary pyridinoline/Cr and deoxypyridinoline/Cr decreased significantly in the treated group (p < 0.05), but not in the control group. Serum osteocalcin levels remained unchanged in both groups. Intact parathyroid hormone levels decreased significantly (p < 0.05) and calcitonin levels significantly increased in the treated group (p < 0.05), but these changes were not observed in the control group. These data clearly demonstrate that 0.75 microgram of 1-alpha-(OH)D3 maintained bone mass by reducing bone resorption by modulation of calcium-regulating hormones. Temporarily increased urinary calcium excretion was observed in control group, but did not appear to be effective in modulating bone turnover.