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The clinical value of regular thyroid function tests during amiodarone treatment
Stan Benjamens1, Robin P F Dullaart1, Wim J Sluiter1
1Department of Internal MedicineDivision of Endocrinology.
European Journal of Endocrinology
|April 21, 2017
Summary
Regular thyroid monitoring for amiodarone-induced thyroid dysfunction (AIT/AIH) may be unreliable. Many patients developing overt AIT/AIH showed no prior subclinical signs, questioning the value of routine screening.
Area of Science:
- Cardiology
- Endocrinology
- Pharmacology
Background:
- Amiodarone is crucial for maintaining sinus rhythm in arrhythmia patients.
- Thyroid dysfunction, including amiodarone-induced thyrotoxicosis (AIT) and amiodarone-induced hypothyroidism (AIH), is a frequent adverse effect.
- The unpredictable onset of AIT and AIH makes long-term monitoring of thyroid function uncertain.
Purpose of the Study:
- To retrospectively evaluate the frequency of subclinical thyroid dysfunction preceding overt amiodarone-induced thyroid dysfunction (AIT/AIH).
- To assess the predictive value of subclinical thyroid dysfunction for overt AIT/AIH in amiodarone-treated patients.
Main Methods:
- Retrospective analysis of 303 patients treated with amiodarone (1984-2007).
- Defined AIT (low TSH, high FT4), AIH (high TSH, low FT4), subclinical AIT (low TSH, normal FT4), and subclinical AIH (high TSH, normal FT4).
- Documented the occurrence of subclinical thyroid dysfunction prior to overt AIT/AIH.
Main Results:
- Over a median follow-up of 2.8 years, 44 patients developed AIT and 33 developed AIH.
- In 55% of patients with AIT/AIH, earlier thyroid function tests showed no subclinical thyroid dysfunction.
- In 45% of patients, AIT/AIH was preceded by subclinical AIT or AIH (16/44 for AIT, 19/33 for AIH).
Conclusions:
- A significant proportion of patients developing AIT/AIH did not exhibit prior subclinical thyroid dysfunction.
- Less than half of patients with subclinical thyroid dysfunction progressed to overt AIT/AIH.
- The findings suggest a need to reconsider the utility of regular thyroid function testing for predicting overt thyroid dysfunction in amiodarone-treated patients.