Autonomous functioning thyroid areas (AFTA), frequently associated to heart arrhythmias, are often occult and may be associated to TSH values in the low-normal range. Despite the administration of an individually tailored dose (ITD) of thyroxine (T4) in the treatment of multinodular goitre (MNG), a serum TSH lower than expected may be obtained as a consequence of the presence of AFTA. This study was aimed at characterizing the existence of hidden AFTA in patients hyperresponding to treatment with an ITD of thyroxine. In a cohort of about 3000 consecutively examined outpatients, we assessed 94 patients (84 F and 10 M; median age=56 years) with MNG in treatment with ITD, who showed an unexpected lower serum TSH as compared to the one observed in a reference group (n = 123; 109 F and 14 M; median age=54 years) in whom iodine and drug interferences, as well as AFTA, were positively excluded. Patients in the study group showed significantly lower median TSH (0.052 vs 0.20 mU/l, P < 0.0001), despite a significantly lower dose administered (1.19 vs 1.49 g/Kg/day, P < 0.0001). When separately analyzed according to age, these differences were confirmed both in adult patients <60 years (median TSH:0.06 vs 0.2 mU/l, P < 0.0001; median T4 dose:1.29 vs 1.56 g/Kg/day, P < 0.0001) and in older patients >60 years (median TSH:0.05 vs 0.22 mU/l, P < 0.0025; median T 4 dose:0.94 vs 1.33 g/Kg/day, P < 0.0005). Interestingly, when treatment was withdrawn, 86/94 patients (91.5%) had serum TSH in the normal range and the median TSH of the whole study group was 1.09 mU/l. The presence of autonomous functioning areas has been detected, through thyroid scintiscan and radioactive iodine uptake test (RAIU- 4 th and 24 th hour), in 65 out of 94 patients (69%). RAIU at 4 th hour (17 vs 13%, P < 0.0199) and 24 th hour (33.5 vs 28%, P < 0.001) were both significantly higher in patients with autonomous functioning areas. These results show that the TD of T4 represents a novel tool to detect hidden autonomous functioning thyroid areas
the individually tailored thyroxine dose as a tool to unveil occult autonomous thyroid functioning areas / Santaguida, MARIA GIULIA; Brusca, Nunzia; Virili, Camilla; DEL DUCA, SUSANNA CARLOTTA; Gatto, Ilenia; Cellini, Miriam; L., Gargano; Centanni, Marco. - In: EUROPEAN THYROID JOURNAL. - ISSN 2235-0640. - vol. 3, suppl. 1, 2014:(2014), pp. 177-177.
the individually tailored thyroxine dose as a tool to unveil occult autonomous thyroid functioning areas
SANTAGUIDA, MARIA GIULIA;BRUSCA, NUNZIA;VIRILI, CAMILLA;DEL DUCA, SUSANNA CARLOTTA;GATTO, ILENIA;CELLINI, MIRIAM;CENTANNI, Marco
2014
Abstract
Autonomous functioning thyroid areas (AFTA), frequently associated to heart arrhythmias, are often occult and may be associated to TSH values in the low-normal range. Despite the administration of an individually tailored dose (ITD) of thyroxine (T4) in the treatment of multinodular goitre (MNG), a serum TSH lower than expected may be obtained as a consequence of the presence of AFTA. This study was aimed at characterizing the existence of hidden AFTA in patients hyperresponding to treatment with an ITD of thyroxine. In a cohort of about 3000 consecutively examined outpatients, we assessed 94 patients (84 F and 10 M; median age=56 years) with MNG in treatment with ITD, who showed an unexpected lower serum TSH as compared to the one observed in a reference group (n = 123; 109 F and 14 M; median age=54 years) in whom iodine and drug interferences, as well as AFTA, were positively excluded. Patients in the study group showed significantly lower median TSH (0.052 vs 0.20 mU/l, P < 0.0001), despite a significantly lower dose administered (1.19 vs 1.49 g/Kg/day, P < 0.0001). When separately analyzed according to age, these differences were confirmed both in adult patients <60 years (median TSH:0.06 vs 0.2 mU/l, P < 0.0001; median T4 dose:1.29 vs 1.56 g/Kg/day, P < 0.0001) and in older patients >60 years (median TSH:0.05 vs 0.22 mU/l, P < 0.0025; median T 4 dose:0.94 vs 1.33 g/Kg/day, P < 0.0005). Interestingly, when treatment was withdrawn, 86/94 patients (91.5%) had serum TSH in the normal range and the median TSH of the whole study group was 1.09 mU/l. The presence of autonomous functioning areas has been detected, through thyroid scintiscan and radioactive iodine uptake test (RAIU- 4 th and 24 th hour), in 65 out of 94 patients (69%). RAIU at 4 th hour (17 vs 13%, P < 0.0199) and 24 th hour (33.5 vs 28%, P < 0.001) were both significantly higher in patients with autonomous functioning areas. These results show that the TD of T4 represents a novel tool to detect hidden autonomous functioning thyroid areasI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
