Calcitonin production: an examination of the regulatory effects of extracellular calcium and 1,25-dihydroxyvitamin D3.

Acute elevations of the serum calcium concentration stimulate release of preformed calcitonin. Whether chronic alterations of the serum calcium of 1,25 dihydroxyvitamin D3 concentrations cause an effect on synthesis or secretion of this major calcium-regulating hormone has not been determined with certainty. Recent studies, including those presented in this manuscript, indicate that 1,25 dihydroxyvitamin D3 and, perhaps, increases of the serum calcium concentration inhibit transcription of the calcitonin gene resulting in decreased production of calcitonin. Inhibition of calcitonin production in the hypercalcemic or vitamin D toxic patient may play a role in the pathophysiology of these conditions.