Potency and tolerance of calcitonin stimulation with high-dose calcium versus pentagastrin in normal adults.

OBJECTIVE

The objectives of the study was to compare pentagastrin- and calcium-stimulated serum human calcitonin (hCT) levels for nonsmoking healthy adults without evidence of thyroid disorders and determine reference ranges of basal and pentagastrin- and calcium-stimulated serum hCT levels.

DESIGN

This was a healthy volunteer study including within-group and intergroup comparisons.

SETTING

The study was conducted at a tertiary referral center.

SUBJECTS

Subjects included 50 healthy, nonsmoking volunteers (25 female; aged 22-57 yr) without evidence of thyroid abnormality.

INTERVENTIONS

hCT was measured using a calcitonin two-site automated chemiluminescent immunometric assay (the most common hCT assay in clinical practice) in serum samples obtained before and 2, 5, and 15 min after iv stimulation using pentagastrin, 0.5 microg/kg body weight, or calcium gluconate, 2.5 mg/kg.

MAIN OUTCOME MEASURES

Reference ranges for basal, unstimulated, and pentagastrin- or calcium-stimulated hCT and pentagastrin and calcium tolerability in healthy adults were measured.

RESULTS

The 95th percentile basal hCT values did not differ between males and females (5.0 vs. 5.7 pg/ml). The 95th percentile maximal stimulated hCT values rose distinctly after pentagastrin (peak men, 37.8 pg/ml; women, 26.2 pg/ml) and even more so after calcium (peak men, 131.1 pg/ml, women, 90.2 pg/ml). No hCT increase was detected in four of 25 men and 12 of 25 women after pentagastrin vs. none of 24 men and two of 18 women after calcium. Calcium was associated with fewer and less intense adverse effects than was pentagastrin.

CONCLUSION

High-dose calcium is a more potent and better-tolerated hCT stimulator than is pentagastrin. The reference ranges for basal and stimulated hCT established via automated chemiluminescent assay were lower than those reported for other assays.