PDN-21: possible tumor marker for medullary thyroid carcinoma.

The plasma level of PDN-21 was measured by RIA in 10 patients with medullary thyroid carcinoma (MTC). All 10 patients with MTC had extremely elevated PDN-21 levels. The correlations between PDN-21, calcitonin gene-related peptide, and calcitonin, (all of which are calcitonin gene products) were significant (P less than .001) in the 10 MTC patients. This study suggests that PDN-21, as well as calcitonin, may be a useful marker for the detection of patients with MTC.