Evaluation of the First Automated Thyroglobulin Assay

Abstract

The aim of this study was to investigate technical and analytical performance of the first automated thyroglobulin (Tg) assay (DPC-Immulite ® ; Diagnostic Products Corporation, Los Angeles, USA). In imprecision studies using several human serum pools ranging from 21 to 58 replicates, a coefficient of variation of 9.0 % was obtained at a mean Tg concentration of 0.84 ng/ml and of 6.1 % at a Tg concentration of 62.1 ng/ml. In a method comparison with a non-automated assay (BRAHMS LUMItest Tg ® , BRAHMS, Berlin, Germany) using 383 sera of 303 patients with thyroid carcinoma, regression analysis according to Passing and Bablock yielded in the following equation: Immulite Tg=1.6 x BRAHMS Tg -0.1 ng/ml (Pearson's r=0.979).Sera obtained from 59 patients with thyroid carcinoma enabled comparative follow-up studies; in all cases qualitative agreement was found with regard to increase or decrease of serum Tg; in eight cases, however, Tg was detected with the Immulite assay but not with the BRAHMS assay. Further follow-up proved the presence of thyroid tissue in these patients. From these and further methodological data (dilution linearity, interference studies, carry-over study, high-dose hook properties, and short report time) it is concluded that the DPC-Immulite Tg assay meets the requirements of routine diagnostic use.

Clinical relevance of highly sensitive Tg assay in monitoring patients treated for differentiated thyroid cancer

“…Immulite® platform Tg immunoassay (Diagnostic Products Corporation, Los Angeles, CA), a chemiluminescent, fully automated technique with a functional sensitivity of 0·9 µg/l stated in the DPC assay package insert, was utilized for standard, routine Tg measurement 8,21 …”

Serum Tg—A Sensitive Marker of Thyroid Abnormalities and Iodine Deficiency in Epidemiological Studies

“…In 12 consecutive assays, the intraassay and interassay variations (coefficients of variation) for single determinations for controls with average Tg concentrations of 8.1, 45, and 154 g/liter were (intra) 5.3, 2.8, and 4.2% and (inter) 6.8, 4.5, and 3.3%. The assay was calibrated by the use of an in-house standardization procedure at BRAHMS; and for comparison to CRM457 calibrated assays, the values of LUMItest should be multiplied by 1.6 (manufacturer's information) (24).…”

Outcomes and Prognostic Factors in Radioiodine Refractory Differentiated Thyroid Carcinomas

“…Tg was measured using an immunochemiluminescence assay (LUMItest Tg; BRAHMS, Berlin, Germany, http:// www.brahms.de), according to the manufacturer's instructions, and was correlated with thyroid-stimulating hormone (TSH) value [20].The limit ofquantification of the method was 0.3 ng/mL. The presence of autoantibodies against Tg (TgAb) was screened by a specific radioimmunoassay (DYNOtest anti-TGn; BRAHMS Diagnostica).…”