Luca Tomisti1, Giuseppe Rossi1, Luigi Bartalena1, Enio Martino1, Fausto Bogazzi2. 1. Endocrinology UnitDepartment of Clinical and Experimental Medicine, University of Pisa, Ospedale Cisanello, Via Paradisa, 2, 56124 Pisa, ItalyEndocrine UnitDepartment of Clinical and Experimental Medicine, University of Insubria, 21100 Varese, ItalyUnit of Epidemiology and BiostatisticsInstitute of Clinical Physiology, National Research Council, 56184 Pisa, Italy. 2. Endocrinology UnitDepartment of Clinical and Experimental Medicine, University of Pisa, Ospedale Cisanello, Via Paradisa, 2, 56124 Pisa, ItalyEndocrine UnitDepartment of Clinical and Experimental Medicine, University of Insubria, 21100 Varese, ItalyUnit of Epidemiology and BiostatisticsInstitute of Clinical Physiology, National Research Council, 56184 Pisa, Italy fausto.bogazzi@med.unipi.it fbogazzi@hotmail.com.
Abstract
OBJECTIVE: Considering the different pathogenic mechanisms of the two main forms of amiodarone-induced thyrotoxicosis (AIT), we ascertained whether this results in a different onset time as well. DESIGN AND METHODS: We retrospectively analyzed the clinical records of 200 consecutive AIT patients (157 men and 43 women; mean age 62.2±12.6 years) referred to our Department from 1987 to 2012. The onset time of AIT was defined as the time elapsed from the beginning of amiodarone therapy and the first diagnosis of thyrotoxicosis, expressed in months. Factors associated with the onset time of AIT were evaluated by univariate and multivariate analyses. RESULTS: The median onset time of thyrotoxicosis was 3.5 months (95% CI 2-6 months) in patients with type 1 AIT (AIT1) and 30 months (95% CI 27-32 months, P<0.001) in those with type 2 AIT (AIT2). Of the total number of patients, 5% with AIT1 and 23% with AIT2 (P=0.007) developed thyrotoxicosis after amiodarone withdrawal. Factors affecting the onset time of thyrotoxicosis were the type of AIT and thyroid volume (TV). CONCLUSIONS: The different pathogenic mechanisms of the two forms of AIT account for different onset times of thyrotoxicosis in the two groups. Patients with preexisting thyroid abnormalities (candidate to develop AIT1) may require a stricter follow-up during amiodarone therapy than those usually recommended. In AIT1, the onset of thyrotoxicosis after amiodarone withdrawal is rare, while AIT2 patients may require periodic tests for thyroid function longer after withdrawing amiodarone.
OBJECTIVE: Considering the different pathogenic mechanisms of the two main forms of amiodarone-induced thyrotoxicosis (AIT), we ascertained whether this results in a different onset time as well. DESIGN AND METHODS: We retrospectively analyzed the clinical records of 200 consecutive AIT patients (157 men and 43 women; mean age 62.2±12.6 years) referred to our Department from 1987 to 2012. The onset time of AIT was defined as the time elapsed from the beginning of amiodarone therapy and the first diagnosis of thyrotoxicosis, expressed in months. Factors associated with the onset time of AIT were evaluated by univariate and multivariate analyses. RESULTS: The median onset time of thyrotoxicosis was 3.5 months (95% CI 2-6 months) in patients with type 1 AIT (AIT1) and 30 months (95% CI 27-32 months, P<0.001) in those with type 2 AIT (AIT2). Of the total number of patients, 5% with AIT1 and 23% with AIT2 (P=0.007) developed thyrotoxicosis after amiodarone withdrawal. Factors affecting the onset time of thyrotoxicosis were the type of AIT and thyroid volume (TV). CONCLUSIONS: The different pathogenic mechanisms of the two forms of AIT account for different onset times of thyrotoxicosis in the two groups. Patients with preexisting thyroid abnormalities (candidate to develop AIT1) may require a stricter follow-up during amiodarone therapy than those usually recommended. In AIT1, the onset of thyrotoxicosis after amiodarone withdrawal is rare, while AIT2 patients may require periodic tests for thyroid function longer after withdrawing amiodarone.
Authors: L Tomisti; C Urbani; G Rossi; F Latrofa; C Sardella; L Manetti; I Lupi; C Marcocci; L Bartalena; O Curzio; E Martino; F Bogazzi Journal: J Endocrinol Invest Date: 2016-01-13 Impact factor: 4.256