BACKGROUND: Recombinant human thyrotropin (rhTSH) stimulation is frequently used to assess the disease status of patients treated for differentiated thyroid cancer (DTC) when basal (unstimulated) thyroglobulin (b-Tg) is below the assay sensitivity limit. The objective of this study was to determine relationships between the b-Tg and the 72-hour rhTSH-stimulated Tg (rhTSH-Tg) using a second-generation immunochemiluminometric assay with a functional sensitivity of 0.05 ng/mL (microg/L). METHODS: Serum Tg was measured in paired b-Tg and rhTSH-Tg specimens from 1029 rhTSH tests performed on 849 TgAb-negative patients during long-term monitoring for DTC. RESULTS: Basal Tg correlated with rhTSH-Tg across b-Tg concentrations ranging from 0.05 to 1000 ng/mL (microg/L) (r = 0.85, p < 0.0001). The b-Tg concentration was unrelated to age, sex, basal TSH, 72-hour TSH, or the Tg fold response (rhTSH-Tg/b-Tg). Further, only 2/655 (0.3%) tests with b-Tg below 0.1 ng/mL (microg/L) had rhTSH-Tg above 2.0 ng/mL (microg/L) (2.9 and 3.8 ng/mL [microg/L], respectively). Thirty-three patients with three or more rhTSH tests performed over a 2- to 5-year period displayed high indexes of individuality for both the 72-hour TSH and the Tg fold response (indexes of individuality = 0.30 and 0.38, respectively). Basal Tg measured using a first-generation assay with a functional sensitivity of 0.9 ng/mL (microg/L) failed to reliably detect an rhTSH-Tg response above 2.0 ng/mL (microg/L). CONCLUSIONS: An rhTSH-Tg response above 2.0 ng/mL (microg/L) was highly unlikely when b-Tg was below 0.1 ng/mL (microg/L). Second-generation b-Tg measurements correlated with the degree of rhTSH-Tg stimulation and thus the likelihood of having rhTSH-Tg above the customary cut-off of 2.0 ng/mL (microg/L), whereas b-Tg measured by a first-generation assay did not. Correlations between four different assays showed that the use of a fixed Tg cut-off was influenced by assay selection. Patients receiving repetitive rhTSH tests had highly reproducible rhTSH-Tg/b-Tg fold responses, suggesting that repetitive testing is unnecessary and that second-generation measurement of b-Tg trends without rhTSH stimulation would be satisfactory for the long-term monitoring of most patients with DTC.
BACKGROUND: Recombinant human thyrotropin (rhTSH) stimulation is frequently used to assess the disease status of patients treated for differentiated thyroid cancer (DTC) when basal (unstimulated) thyroglobulin (b-Tg) is below the assay sensitivity limit. The objective of this study was to determine relationships between the b-Tg and the 72-hour rhTSH-stimulated Tg (rhTSH-Tg) using a second-generation immunochemiluminometric assay with a functional sensitivity of 0.05 ng/mL (microg/L). METHODS: Serum Tg was measured in paired b-Tg and rhTSH-Tg specimens from 1029 rhTSH tests performed on 849 TgAb-negative patients during long-term monitoring for DTC. RESULTS: Basal Tg correlated with rhTSH-Tg across b-Tg concentrations ranging from 0.05 to 1000 ng/mL (microg/L) (r = 0.85, p < 0.0001). The b-Tg concentration was unrelated to age, sex, basal TSH, 72-hour TSH, or the Tg fold response (rhTSH-Tg/b-Tg). Further, only 2/655 (0.3%) tests with b-Tg below 0.1 ng/mL (microg/L) had rhTSH-Tg above 2.0 ng/mL (microg/L) (2.9 and 3.8 ng/mL [microg/L], respectively). Thirty-three patients with three or more rhTSH tests performed over a 2- to 5-year period displayed high indexes of individuality for both the 72-hour TSH and the Tg fold response (indexes of individuality = 0.30 and 0.38, respectively). Basal Tg measured using a first-generation assay with a functional sensitivity of 0.9 ng/mL (microg/L) failed to reliably detect an rhTSH-Tg response above 2.0 ng/mL (microg/L). CONCLUSIONS: An rhTSH-Tg response above 2.0 ng/mL (microg/L) was highly unlikely when b-Tg was below 0.1 ng/mL (microg/L). Second-generation b-Tg measurements correlated with the degree of rhTSH-Tg stimulation and thus the likelihood of having rhTSH-Tg above the customary cut-off of 2.0 ng/mL (microg/L), whereas b-Tg measured by a first-generation assay did not. Correlations between four different assays showed that the use of a fixed Tg cut-off was influenced by assay selection. Patients receiving repetitive rhTSH tests had highly reproducible rhTSH-Tg/b-Tg fold responses, suggesting that repetitive testing is unnecessary and that second-generation measurement of b-Tg trends without rhTSH stimulation would be satisfactory for the long-term monitoring of most patients with DTC.
Authors: Gary L Francis; Steven G Waguespack; Andrew J Bauer; Peter Angelos; Salvatore Benvenga; Janete M Cerutti; Catherine A Dinauer; Jill Hamilton; Ian D Hay; Markus Luster; Marguerite T Parisi; Marianna Rachmiel; Geoffrey B Thompson; Shunichi Yamashita Journal: Thyroid Date: 2015-07 Impact factor: 6.568
Authors: Scott A Rivkees; Ernest L Mazzaferri; Frederik A Verburg; Christoph Reiners; Markus Luster; Christopher K Breuer; Catherine A Dinauer; Robert Udelsman Journal: Endocr Rev Date: 2011-08-31 Impact factor: 19.871
Authors: Alberto S Tresoldi; Laura F Sburlati; Marcello Rodari; Mink S Schinkelshoek; Michela Perrino; Simone De Leo; Laura Montefusco; Paolo Colombo; Maura Arosio; Andrea Gerardo Antonio Lania; Laura Fugazzola; Arturo Chiti Journal: J Endocrinol Invest Date: 2014-05-21 Impact factor: 4.256
Authors: Cláudia C D Nakabashi; Teresa S Kasamatsu; Felipe Crispim; Claudia A Yamazaki; Cléber P Camacho; Danielle M Andreoni; Rosalia P Padovani; Elza S Ikejiri; Maria C O M Mamone; Flávia C Aldighieri; Jairo Wagner; Jairo T Hidal; José G H Vieira; Rosa P M Biscolla; Rui M B Maciel Journal: Eur Thyroid J Date: 2014-03-12
Authors: Bryan R Haugen; Erik K Alexander; Keith C Bible; Gerard M Doherty; Susan J Mandel; Yuri E Nikiforov; Furio Pacini; Gregory W Randolph; Anna M Sawka; Martin Schlumberger; Kathryn G Schuff; Steven I Sherman; Julie Ann Sosa; David L Steward; R Michael Tuttle; Leonard Wartofsky Journal: Thyroid Date: 2016-01 Impact factor: 6.568
Authors: Laticia A Valle; Revital L Gorodeski Baskin; Kyle Porter; Jennifer A Sipos; Raheela Khawaja; Matthew D Ringel; Richard T Kloos Journal: Thyroid Date: 2013-02 Impact factor: 6.568