Calcitonin secretion in hyperthyroidism.

The level of circulatory calcitonin was determined by the RIA method in 45 hyperthyroid patients in evolution, before and after calcium stimulation or after pentagastrin injection. The basal calcitonin secretion was increased in only 7 of the 45 patients studied, exceeding 500 pg/ml. After a slow calcium loading the mean of calcitonin increased, but with variable individual values. The rapid calcium loading was not followed by significant increases after 30 minutes. After pentagastrin a secretory peak of over 1,800 pg/ml was obtained in 4/5 cases. Results point out the state of the calcitonin-secreting system in hyperthyroidism and its possible role in the skeleton protection in these patients.