Enhanced calcitonin release in chronic renal failure depending on the absence of severe secondary hyperparathyroidism

In 27 patients with end-stage chronic renal failure an elevated calcitonin (CT) and parathyroid hormone was found. On stimulation with Ca i.v. there were 9 cases in whom delta CT proved to be higher than the maximal response of 50 pg ml-1 in controls. Supranormal CT responses were found predominantly in patients with normal alkaline phosphatase, who as a group increased their CT from 94.5 +/- 61 to 142.0 +/- 94 pg ml-1 (p less than 0.02). In contrast to this, patients with elevated alkaline phosphatase who also had a higher level of parathyroid hormone maintained unchanged CT on Ca stimulation. It is concluded that in chronic renal failure with severe secondary hyperparathyroidism, delta CT on stimulation is normal, while an enhanced delta CT often exists when hyperparathyroidism is of insufficient degree to cause a raised alkaline phosphatase.