Could primary hyperparathyroidism-related hypercalcemia induce hypercalcitoninemia?

AIMS: To determine if primary hyperparathyroidism (pHPT) per se may be responsible of hypercalcitoninemia. pHPT induces chronic hypercalcemia that should be expected to be a potential stimulatory pathway of calcitonin (CT) secretion and to cause hypercalcitoninemia. METHOD: We studied relationships between CT and pHPT-related chronic hypercalcemia in 122 patients aged 25-83 years who underwent parathyroid surgery. CT, calcium and PTH plasma levels were measured in all patients preoperatively. CT was measured by a current immunometric assay specific of mature CT monomer. RESULTS: Of our 122 patients with pHPT-related hypercalcemia, 120 (98.4%) had normal CT values of less than 10 pg/ml and two (1.6%) exhibited a mildly increased CT above 10 pg/ml (11 and 12 pg/ml, respectively). We evidenced no relationship between CT and calcium level or PTH level. CONCLUSIONS: Chronic pHPT-related hypercalcemia per se does not cause hypercalcitoninemia. The finding of pHPT concomitant with high CT levels should raise suspicion of multiple endocrine neoplasia type 2A.