Comparison of immunoradiometric assays for determination of thyroglobulin: a validation study

Abstract

In this study we compared and validated commercial immunoradiometric assays (IRMA) to determine thyroglobulin (Tg) levels in serum. From a set of 440 samples, 68 were selected to calculate the validation parameters and the clinical performance of the assays. The commercial kits evaluated were the Tg-CTK (DiaSorin), IRMAZenco Tg (ZenTech), and SELco-Tg (Medipan). We found that 21% of the collected samples were in the critical range of concentration. Detection limits were calculated as being below 3 microg/L. Intra- and inter-reproducibility were lower than 3.1% and 9.2%, respectively. Dilution and recovery studies provided quantitative determinations. Correlation regression coefficients from the results of the methods were obtained. The determined concentrations were compared with the clinical evidence of disease. Variation in the 125-iodine-labeled antibody concentration and control charts showed the robustness of the methods. Analysis time and the simplicity of the methods were also evaluated. Reliable Tg determination is important for monitoring patients with differentiated thyroid cancer (DTC), controlling other thyroid diseases, and assessing the quality of imaging techniques. A strategy for verification and comparison based on analytical parameters and clinical performance is proposed.

Does 131I Radioactivity Interfere with Thyroglobulin Measurement in Patients Undergoing Radioactive Iodine Therapy with Recombinant Human TSH?

“…Despite debates on the discordance between commercial assay kits [2][3][4][5][6], highsensitivity human Tg IRMA can detect serum Tg concentrations of 0.2 ng/ml, and serum Tg concentrations <0.2 ng/ml are used to indicate complete remission [7]. Because the serum Tg level is used for surveillance after total thyroidectomy to evaluate the residual and recurrent differentiated thyroid cancer (DTC), accurate estimation of the serum Tg level is important [8].…”

Immunoradiometric determination of thyroglobulin in serum samples by time calibration transfer

“…This faster degradation process was confirmed using different radiolabeled immunoreagents with similar analytical and clinical performance (18). The kinetic constants were -0.019"0.003 and -0.014"0.005 day y1 for Tg-CTK and IRMAZenco Tg, respectively.…”

Laboratory reproducibility of biochemical markers of bone turnover in clinical practice

“…In the past, some published studies comparing laboratory performance have published data without naming the laboratories [ 12 , 13 ], but reaction in the literature has included the belief that the laboratories should be identified [ 14 ]; the present study provides laboratories' names in order that the results and discussion generated be as useful as possible to clinicians. The identification of laboratories by name is similar to the identification of commercial assays by name when such assays are compared, and this is not uncommon in the literature [ 15 – 17 ].…”