scholarly journals Approach to the Patient with a Positive Serum Thyroglobulin and a Negative Radioiodine Scan after Initial Therapy for Differentiated Thyroid Cancer

2008 ◽  
Vol 93 (5) ◽  
pp. 1519-1525 ◽  
Author(s):  
Richard T. Kloos
Keyword(s):  
Thyroid Cancer ◽  
Differentiated Thyroid Cancer ◽  
Initial Therapy ◽  
Serum Thyroglobulin ◽  
Positive Serum ◽  
Radioiodine Scan

scholarly journals Serum Thyroglobulin (Tg) Monitoring of Patients with Differentiated Thyroid Cancer Using Sensitive (Second-Generation) Immunometric Assays Can Be Disrupted by False-Negative and False-Positive Serum Thyroglobulin Autoantibody Misclassifications

2014 ◽  
Vol 99 (12) ◽  
pp. 4589-4599 ◽  
Author(s):  
Carole Spencer ◽  
Ivana Petrovic ◽  
Shireen Fatemi ◽  
Jonathan LoPresti
Keyword(s):  
Thyroid Cancer ◽  
False Positive ◽  
Differentiated Thyroid Cancer ◽  
Operating Characteristic ◽  
Characteristic Curve ◽  
False Negative ◽  
False Negatives ◽  
Serum Thyroglobulin ◽  
Positive Serum ◽  
Operating Characteristic Curve

Context: Reliable thyroglobulin (Tg) autoantibody (TgAb) detection before Tg testing for differentiated thyroid cancer (DTC) is critical when TgAb status (positive/negative) is used to authenticate sensitive second-generation immunometric assay (2GIMA) measurements as free from TgAb interference and when reflexing “TgAb-positive” sera to TgAb-resistant, but less sensitive, Tg methodologies (radioimmunoassay [RIA] or liquid chromatography-tandem mass spectrometry [LC-MS/MS]). Objective: The purpose of this study was to assess how different Kronus (K) vs Roche (R) TgAb method cutoffs for “positivity” influence false-negative vs false-positive serum TgAb misclassifications that may reduce the clinical utility of reflex Tg testing. Methods: Serum Tg2GIMA, TgRIA, and TgLC-MS/MS measurements for 52 TgAb-positive and 37 TgAb-negative patients with persistent/recurrent DTC were compared. A total of 1426 DTC sera with TgRIA of ≥1.0 μg/L had false-negative and false-positive TgAb frequencies determined using low Tg2GIMA/TgRIA ratios (<75%) to indicate TgAb interference. Results: TgAb-negative patients with disease displayed Tg2GIMA, TgRIA, and TgLC-MS/MS serum discordances (% coefficient of variation = 24 ± 20%, range, 0%–100%). Of the TgAb-positive patients with disease, 98% had undetectable/lower Tg2GIMA vs either TgRIA or TgLC-MS/MS (P < .01), whereas 8 of 52 (15%) had undetectable Tg2GIMA + TgLC-MS/MS associated with TgRIA of ≥1.0 μg/L. Receiver operating characteristic curve analysis reported more sensitivity for TgAb method K vs R (81.9% vs 69.1%, P < .001), but receiver operating characteristic curve cutoffs (>0.6 kIU/L [K] vs >40 kIU/L [R]) had unacceptably high false-negative frequencies (22%–32%), whereas false positives approximated 12%. Functional sensitivity cutoffs minimized false negatives (13.5% [K] vs 21.3% [R], P < .01) and severe interferences (Tg2GIMA, <0.10 μg/L) (0.7% [K] vs 2.4% [R], P < .05) but false positives approximated 23%. Conclusions: Reliable detection of interfering TgAbs is method and cutoff dependent. No cutoff eliminated both false-negative and false-positive TgAb misclassifications. Functional sensitivity cutoffs were optimal for minimizing false negatives but have inherent imprecision (20% coefficient of variation) that, exacerbated by TgAb biologic variability during DTC monitoring, could cause TgAb status to fluctuate for patients with low TgAb concentrations, prompting unnecessary Tg method changes and disrupting Tg monitoring. Laboratories using reflexing should limit Tg method changes by considering a patient's Tg + TgAb testing history in addition to current TgAb status before Tg method selection.

The role of preoperative serum thyroglobulin values in the diagnosis of differentiated thyroid cancer

2017 ◽  
Author(s):  
Blertina Dyrmishi ◽  
Taulant Olldashi ◽  
Ema Lumi ◽  
Entela Puca ◽  
Dorina Ylli ◽  
...  
Keyword(s):  
Thyroid Cancer ◽  
Differentiated Thyroid Cancer ◽  
Serum Thyroglobulin ◽  
Preoperative Serum

scholarly journals Comparison of Thyroglobulin Concentrations Measured by Two Immunoradiometric Assay

2020 ◽  
Vol 21 (2) ◽  
pp. 121-125
Author(s):  
Vesna Ignjatovic ◽  
Milovan Matovic ◽  
Vladimir Vukomanovic
Keyword(s):  
Thyroid Cancer ◽  
Statistical Analysis ◽  
Differentiated Thyroid Cancer ◽  
Immunoradiometric Assay ◽  
Serum Thyroglobulin ◽  
Specific Test ◽  
Radioiodine Ablation ◽  
Assay Methods ◽  
Positive Correlation Coefficient ◽  
Good Agreement

AbstractCirculating thyroglobulin measurements is a highly specific test in the management of patients affected by differentiated thyroid cancer after total thyroidectomy, followed by radioiodine ablation. The aim of our study was to compare two thyroglobulinimmunoradiometric assays (INEP, Serbia and Cisbio Bioassays, France). Study included 42 patients of both genders with DTC. The subjects were on suppres¬sive doses of levothyroxine and followed up. Results showed concordance between the two assay methods for determining serum thyroglobulin for 39 (92.85%) patients. Statistical analysis showed that there was a direct correlation between two IRMA tests, with a positive correlation coefficient r=0.613 (p 0.05). We concluded that there is good agreement between the two thyroglobulin assays compared in this study.

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