Endocrine changes associated with the human aging process: III. Effect of age on the number of calcitonin immunoreactive cells in the thyroid gland.

The thyroid glands obtained at autopsy from 60 patients ranging in age from 16 to 89 years were immunostained for calcitonin (CT) by the peroxidase-antiperoxidase procedure. The numbers of CT immunoreactive cells identified were 0.99 +/- 1.07/mm2 in the young patients (16 to 39 years of age), 0.99 +/- 1.46/mm2 in the middle-aged (40 to 59 years of age), and 2.97 +/- 3.69/mm2 in the elderly (60 years of age and older). The results were not statistically significant because of the large standard deviation. The CT immunoreactive cells tended to aggregate in clusters in a pattern similar to that seen in C-cell nodules in older persons.