Basal and pentagastrin-stimulated levels of calcitonin in thyroid and peripheral veins during normocalcemia and chronic hypercalcemia in humans.

The calcitonin secretion from the thyroid C-cells was studied with a peroperative method. The calcitonin concentrations in thyroid venous effluent and peripheral veins were determined in patients who underwent operations because of thyroid and parathyroid disease. In normocalcemia the thyroid vein level of calcitonin was significantly higher than that in peripheral vein. In chronic hypercalcemia no gradient over the thyroid was demonstrable. After injection of pentagastrin into a thyroid artery a very pronounced, but transient, increase in calcitonin concentration was registered. No difference in peak value between normo- and hypercalcemia was demonstrable. The peripheral vein level was unchanged. The peroperative method is very sensitive. A marked peak in thyroid vein corresponds to unchanged values in peripheral vein. The method invites further studies with other secretagogues and receptor-blocking substances.