[Katacalcin levels in healthy children and children with spasmophilia]

The calcitonin (CT) gene encodes at least 3 peptides: CT, the 21-aminoacid carboxyl-terminal flanking peptide (katalcin or PDN-21) and CT-gene related peptide. Normal thyroid C-cells as well as malignant ones co-secrete CT and PDN-21 in response to hypercalcemia, so assay of PDN-21 may be an usefull method to assess C-cells secretion. Because of our knowledge no data are available on PDN-21 values in children, we measured this peptide in healthy children and in spasmophilia (Sp), a disease that has been related to CT deficiency. We studied 16 healthy children (9 males, 7 females; aging from 3.0 to 11.6 years) and in 21 patients with diagnosed Sp (8 males, 13 females, aging from 4.6 to 13.0 years). PDN-21 were assayed in whole serum by RIA using synthetic human PDN-21 for standards, 125I-PDN-21 for tracer and specific antiserum. CT was measured the serum of the same subjects by RIA using an ultrasensitive methods. In healthy children PDN-21 serum values were 12.3 +/- 2.0 pg/ml and no significant differences were found between males and females. Children with Sp showed slow higher PDN-21 concentrations (14.0 +/- 1.4 pg/ml) than normals, but the difference was not statistically significant. Also CT values were not significantly different between normal children (21.4 +/- 3.7 pg/ml) and patients with spasmophilia (22.5 +/- 1.8 pg/ml). A high significant positive relation was found between katalcacin and CT levels in normals as well as in spasmophilics. The physiological effects of PDN-21 are actually unknown.(ABSTRACT TRUNCATED AT 250 WORDS)