Amiodarone-induced thyroid dysfunction in a tertiary center in south Brazil

Area of Science:

• Cardiology
• Endocrinology
• Pharmacology

Background:

• Amiodarone is a key antiarrhythmic drug.
• Thyroid dysfunction is a known side effect of amiodarone.
• Limited data exists on amiodarone-induced thyroid dysfunction in southern Brazil.

Purpose of the Study:

• Determine the prevalence of amiodarone-induced thyroid dysfunction.
• Identify factors associated with amiodarone-induced thyroid dysfunction.
• Evaluate the reliability of clinical scores for diagnosing thyroid abnormalities.

Main Methods:

• A clinical and laboratory evaluation was performed on 195 amiodarone users.
• Prevalence of hyperthyroidism, hypothyroidism, and elevated T4 was assessed.
• Association of thyroid dysfunction with variables like autoimmunity and gender was analyzed.
• Sensitivity of clinical scores for hypo- and hyperthyroidism was calculated.

Main Results:

• Prevalence: 2.1% hyperthyroid, 25.1% hypothyroid, 9.2% high T4.
• Thyroid autoimmunity (OR 4.8) and male gender (OR 1.86 trend) were associated with dysfunction.
• Clinical scores showed 100% sensitivity for hyperthyroidism but only 8% for hypothyroidism.

Conclusions:

• The low prevalence of amiodarone-induced hypothyroidism suggests iodine sufficiency in the region.
• Clinical scores are highly sensitive for hyperthyroidism, aiding early detection.
• Screening for thyroid dysfunction, especially in males or those with positive microsomal antibodies, is recommended for amiodarone users.