The study shows that giving human calcitonin to people reduces their growth hormone (GH) spikes, especially when the body is trying to release GH after low blood sugar or after a GH‑releasing hormone signal. It also causes a brief, small rise in prolactin and thyroid‑stimulating hormone, but doesn’t change calcium or magnesium levels. In short, calcitonin seems to block GH release, but not by the usual pathways.

To determine whether human calcitonin inhibits GH secretion in man, as has been described for salmon calcitonin, the effect of an i.v. bolus of human calcitonin or saline on GH release after either insulin-induced hypoglycaemia or the administration of GH-releasing hormone (GHRH) or saline was studied. After the injection of calcitonin, no spontaneous GH surges were seen; the GH response to hypoglycaemia was diminished and the response to GHRH almost completely suppressed. Administration of calcitonin also caused a small and transient rise in plasma PRL and TSH but not LH levels, and no change in the integrated PRL or TSH response. Calcium and magnesium levels did not change. It is concluded that human calcitonin suppresses GH secretion in man, but not by suppressing GHRH and probably not by increasing somatostatin release. In addition, calcitonin has limited PRL and TSH-releasing activity.