Calcium and parathyroid hormone behaviour after exogenous secretin infusion in man

The response of serum calcium, PTH, CT and gastrin to an infusion of secretin (3 CU/kg/h) over a period of 90 min was studied in ten healthy males and two female patients with hypoparathyroidism. In the healthy males serum calcium, after a transient fall, significantly increased at 45 min after the onset of the infusion (P less than 0.001). Serum iPTH rose significantly within 5 min whereas serum CT and gastrin concentrations did not change. The two hypoparathyroid patients did not show any variations in either serum iPTH or calcium. These findings suggest that infusion of pharmacological doses of secretin into normal subjects modifies serum calcium, and that this change is due to PTH release.