Immunoreactive calcitonin in human cerebrospinal fluid.

The cerebrospinal fluid (CSF) of 123 male subjects was studied by RIA for the presence of immunoreactive calcitonin (CT). The hormone could be detected in the CSF of 75% of 63 subjects at a mean (+/- SE) concentration of 11.1 +/- 1.3 pg/ml, with a range of less than 2 to 55 pg/ml. In 31 subjects, simultaneous measurements were made of CSF and plasma CT and there was not significant correlation between them. Column chromatography of a lyophilized pool of CSF from 60 of the subjects demonstrated that most of the CT immunoreactivity eluted with or after radioiodinated human CT. Our studies demonstrate the presence of immunoreactive CT in human CSF but do not provide any direct evidence regarding the source of the immunoreactivity.