Serum calcitonin reference values for calcium stimulation tests by electrochemiluminescence immunoassay in Japanese men with non-medullary thyroid carcinoma.

Abstract

Calcitonin is the most sensitive tumor marker of medullary thyroid carcinoma (MTC) and a calcium stimulation test is used to improve this sensitivity. In Japan, the electrochemiluminescence immunoassay (ECLIA) is currently the only test performed to measure serum calcitonin. There is a gender difference in the reference value of serum calcitonin; however, a reference upper limit for use with ECLIA has been reported only for women, but not for men. We conducted the calcium stimulation test using ECLIA in 21 men with non-medullary thyroid carcinoma (non-MTC), before and after total thyroidectomy. Preoperatively, the basal calcitonin values were within normal limits in all patients. They increased to a mean value of 37.6pg/mL after calcium stimulation, and we calculated that the reference upper limit was 83.7pg/mL. The stimulation test results after total thyroidectomy showed undetectable basal and stimulated calcitonin values in every patient (<0.5pg/mL). To our knowledge, this is the first study to calculate reference values for this stimulation test using an ECLIA in men with non-MTC. We propose that men can be regarded as biochemically cured or as having normal serum calcitonin values when the stimulated calcitonin values obtained by ECLIA are <83.7pg/mL before and <0.5pg/mL after total thyroidectomy.