[Evaluation of an immunoassay for calcitonin]

The calcitonin is the most specific and the most sensitive marker of medullary thyroid carcinoma (MTC) both for screening and postoperative follow-up of the patients. Its measurement is made either remotely , or after stimulation of pentagastrin secretion which the answer is amplified at the carrier of CMT. The aim of this study was to estimate a chimioluminescent method by comparing it with an immunoradiological method, manual, used as reference. Correlation study was done.

Two hundred and sixty three serums (263) were tested among which 64 resulting of healthy subjects and 199 resulting of patients affected) by medullary thyroid carcinoma. Statistical analysis of results was made by a study of correlation with the software OriginLab version 7.0. The manual technique used as reference method is radioimmunological (Elsa hCT, international Cisbio, Gif on Yvette, France). It was compared with a chimioluminescent technique (Nichols Advantage, Nichols Institute Diagnostics, CA, the USA).

The coefficients of correlation obtained between both tests were: r = 0.76 (exactness study), r = 0.91 (after stimulation), r = 0.95 and 0.79 (staged samples), r = 0.99 (M TC patients).

Both techniques correlate strictly and significantly. The correlation coefficients we obtained show us that Nichols Advantage Calcitonin is completely reliable and sensitive for the measurement of the hCT in the follow-up of the CMT.