Immunoenzymatic method for determining thyroglobulin levels in human blood serum]

An inexpensive enzyme immunoassay method was designed for the determination of thyroglobulin concentration in human blood serum. The range of concentrations of thyroglobulin which can be measured by the method is between 6 and 800 ng/ml. The sensitivity of the method is comparable to that of the commercial test kits. The values of thyroglobulin concentration obtained with the use of the described method are strongly correlated (r = 0.946) with those obtained by using the reference method (IRMA kit of Byk, Sweden). The intraassay coefficient of variation ranged from 5.5 to 10.2% and interassay coefficient of variation from 9.5 to 13.2% depending on the thyroglobulin concentration. The upper limit of blood serum thyroglobulin concentration in healthy subjects was 70 ng/ml. The results of thyroglobulin determination obtained with the described method are falsely lowered in the presence of antithyroglobulin antibodies; simultaneous determination of these antibodies is thus necessary in such a case. It seems that the described method may be used for monitoring the patients after surgical treatment of differentiated thyroid cancer aimed at early detection of metastases.