Calcitonin levels in normal women of various ages evaluated with a new sensitive radioimmunoassay.

In order to establish the normal range of serum Calcitonin (CT), evaluated with a new, sensitive radioimmunoassay in normal women of various ages, 67 female subjects were examined. CT levels were detectable in all the subjects, with a reference interval (bounded by the 2.5 and 97.5 percentiles) of 3.6-16.9 pg/ml; a very slight decrease with age was observed (correlation coefficient = -0.24; P = 0.05; regression equation: CT = 9.55--0.042 x age). This assay seems sensitive enough to permit the measurement of CT in physiological conditions.