Can chemiluminescent immunoanalysis of thyroid hormones stand for a reference method?

Abstract

Some analytical properties of chemiluminescent immunoassays (ChLIA) for the estimation of total triiodothyronine (T3), total thyroxine (T4) and thyrotropine (TSH) in serum were studied and compared with radioimmunoanalysis (RIA) as a reference method. Measurement range of ChLIA for T3 is lower, for T4 is equivalent and for TSH is greater than by RIA methods. Analytical sensitivity of ChLIA is better for all three analytes. Also precision of ChLIA is much better. ChLIA method seems to be more resistant to lipaemia. When compared to secondary reference materials, i.e. to commercial control sera, higher accuracy can be evaluated. However, adjustment of the control sera and analytical methods to different primary standards and calibrators, resulting in disagreement of results with asigned values, seems to be evident. With respect to the accuracy of ChLIA further study should be performed involving primary standards. Other interferences except of lipaemia, which we refer to in our work, and problems of specificity also need to be elucidated.