 Print page |
 Email page |
Hypothyroidism is a common adverse effect of amiodarone, usually occurring during the first months of treatment
The background of the study. Hypothyroidism and, less often, hyperthyroidism are well-recognized adverse effects of amiodarone, a drug often given to treat patients with atrial fibrillation, a common cardiac rhythm abnormality (arrhythmia). In this study, serum thyrotropin (TSH) was measured prospectively in a large group of patients who were treated with amiodarone, sotalol (another arrhythmia drug), or placebo.
How the study was done. The study subjects were 612 patients with atrial fibrillation who were randomly assigned to treatment with amiodarone, sotalol, or placebo. For this study, the sotalol and placebo groups were combined into a single control group. Cardiac rhythm was determined by monitoring by telephone. Serum TSH (normal range, 0.35 to 4.5 mU/L) was measured at base line, after three and six months, and every six months thereafter. Thyroxine therapy was initiated at the discretion of the treating physician.
The results of the study. The pretreatment characteristics, including average age, body-mass index, and concurrent diseases (coronary heart disease, diabetes mellitus) of the patients in the amiodarone and control groups were similar.
During therapy, the incidence of low serum TSH values was similar in the two groups, but more patients in the amiodarone group had high serum TSH values (Table).
| Table. Incidence of Low and High Serum TSH Concentrations in the Amiodarone and Control Groups. | ||
| Serum TSH | Amiodarone (n=247) | Sotalol-Placebo (n=299) |
<0.35 mU/L |
13 (5%) |
7 (2%) |
>4.5–10 mU/L |
62 (25%) |
19 (6%) |
>10 mU/L |
12 (5%) |
1 (0.3%) |
Among the patients in the amiodarone group who had high serum TSH values, the values were high at three months in 58 percent and most of remaining cases were detected by one year.
The conclusions of the study. Hypothyroidism, as manifested by high serum TSH concentrations, is common in patients who are treated with amiodarone, usually occurring during the first months of therapy.
The original article. Batcher EL, Tang XC, Singh BN, Singh SN, Reda DJ, Hershman JM, for the SAFE-T investigators. Thyroid function abnormalities during amiodarone therapy for persistent atrial fibrillation. Am J Med 2007;120:880-5.
 Next Article: Reversing the fall in serum triiodothyronine during cardiac surgery does not alter the hemodynamic and metabolic responses to the surgery |
||
| Thyroid Digest Index | | | November 2007 Thyroid Digest |
