[Comparison of efficacy of various methods of thyroglobulin measurements in differentiated thyroid cancer]

Monitoring patients with differentiated thyroid carcinoma (DTC) by thyroglobulin (Tg) measurements requires selecting optimal methods used for detection of this marker. An increase the thyroglobulin concentration in serum is a predictor of tumor recurrence. All serum thyroglobulin assays can be falsified by presence of Tg autoantibodies, which are present in approximately 20% of DTC patients. The aim of this study was a comparison of the clinical utility of two different methods for determining serum Tg concentration in monitoring patients with DTC during thyroxine treatment. Tg concentration was measured in serum samples of 1530 patients with DTC during replacement thyroid hormone using two methods: fluoroimmunometric assay (IFMA) Wallac Delfia Thyroglobulin and immunoradiometric assay (IRMA) Brahms DYNOtest Tg-S. 1847 values of Tg concentration and recovery test detected between 1992 and 1995 years using IFMA methods and 1187 values of Tg and thyroglobulin autoantibodies concentration measured in 2000 year using IRMA methods were also included. The correlation between Tg values in all patients group wasn't good (r = 0.83; p < 0.05), but when we excluded patients with incorrect recovery test determined by IRMA, the correlation factor was higher (r = 0.94; p < 0.05). The estimation of Tg recovery test obtained in IRMA assay eliminated from monitoring only 3% patients with DTC, when IFMA assay excluded nearly 1/5 patients, whereas the estimation Tg autoantibodies 7% from all patients. The IRMA method is the most resistant to interference and allows to monitor a reliably greater group of patients with DTC during thyroxine treatment.