Calcitonin- and katacalcin-like immunoreactivity in human seminal plasma

iCT was determined in 74 patients by direct RIA. A highly significant increase (371 pg/ml) compared with normal serum concentration (100 pg/ml) was observed. There was no correlation between iCT concentration and ejaculate parameters. In addition monomeric bioactive CT and from the same RNA derived KT were determined from a seminal plasma pool gathered from 25 patients. The measured amounts were similar to those found in plasma. Monomeric CT or KT is not responsible for high amounts of iCT in seminal plasma found by direct radioimmunoassay. High amounts of iCT or iKT are due to two heterogenous peptides with greater molecular mass but have no influence on fertility.