Thyroid dysfunction and cardiological management in patients receiving amiodarone.
OBJECTIVE
To determine the prevalence of thyroid dysfunction in patients receiving amiodarone, and the possible associated factors. The study also aimed at assessing the effect of amiodarone on thyroid function through the application of a questionnaire to cardiologists.


METHODS
Fifty-six patients chronically (> 3 months) receiving amiodarone were assessed by measurement of their serum levels of TSH, free T4, total T3, and anti-TPO antibodies. Patients with changes in TSH levels were defined as having thyroid dysfunction (TD).


RESULTS
The prevalence of thyroid dysfunction was 33.9%. No difference was observed between this group and that of patients with no dysfunction, except for the greater prevalence of anti-TPO positivity in patients with TD (P=0.02). Subclinical hypothyroidism was diagnosed in 10 (17.9%) patients and clinical hypothyroidism in 6 (10.7%). The prevalence of subclinical hyperthyroidism was 3.6% and that of clinical hyperthyroidism was 1.8%. Anti-TPO antibodies were positive in 5 (8%) patients (of whom, 4 had thyroid dysfunction). When compared with patients negative for anti-TPO antibodies, that group had a greater prevalence of dysfunction (80% vs 29.4%; P=0.04). Only 49.2% of the cardiologists routinely treated their patients' thyroid function, and the prevalence of the referred dysfunction for most of them ranged from 1 to 10%.


CONCLUSIONS
The prevalence of thyroid dysfunction in our population was high, showing the need for implementing a laboratory routine. The cardiologists disagreed greatly in regard to the type of follow-up required for patients using amiodarone.
Fuks
Anna Gabriela
AG
Hospital Universitário Clementino Fraga Filho, UFRJ, Rio de Janeiro, Brazil. agfuks@yahoo.com.br
Vaisman
Mário
M
Buescu
Alexandru
A
D000638:Amiodarone / Q000009:adverse effects / Q000627:therapeutic use*; D000889:Anti-Arrhythmia Agents / Q000009:adverse effects / Q000627:therapeutic use*; D001938:Brazil / Q000453:epidemiology; D005260:Female; D006331:Heart Diseases / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D013959:Thyroid Diseases / Q000139:chemically induced / Q000453:epidemiology* / Q000276:immunology; D013961:Thyroid Gland / Q000187:drug effects
D000889:Anti-Arrhythmia Agents; D000638:Amiodarone