[AMIODARONE-INDUCED THYROTOXICOSIS - RISK FACTORS AND PREDICTORS OF OUTCOME: A RETROSPECTIVE STUDY]

Amiodarone induced thyrotoxicosis (AIT) occurs with considerable incidence and is associated with significant morbidity and mortality. Factors that predict poor prognosis in this disease have not yet been sufficiently investigated.

We examined the characteristics and short-term clinical outcomes of patients with AIT (up to six months from diagnosis). We evaluated the relationship between T3 and T4 levels at time of presentation and complications associated with AIT.

A retrospective epidemiological study was conducted reviewing all cases diagnosed with thyrotoxicosis and amiodarone consumption of patients treated in the Carmel Medical Center between the years 2004-2008. We examined the characteristics of patients who tend to develop AIT. In addition, we examined whether T3 and T4 levels at the time of presentation were a predictor of a poor prognosis. Three major complications associated with AIT were defined as primary outcomes within six months of diagnosis: 1. mortality; 2. development of AIT-related complications that required hospitalization; 3. the need for thyroidectomy.

A total of 400 patients were diagnosed with thyrotoxicosis and consumed amiodarone. However, only 39 patients met the definition of AIT. The composite outcome of mortality, AIT-related complications and thyroidectomy were found in the vast majority of patients (94.8%, 37 out of 39 participants); 3 (7.6%) died and 35 (89.7%) were hospitalized with AIT-related complications and 8 (20.5%) required thyroidectomy. We found a statistically significant relationship between high T4 levels (above 64.3 mcg/dL or above 3 times the upper limit of the norm) and the composite of two main endpoints: mortality and the need for thyroidectomy in the first half year of diagnosis (P=0.009).

AIT is associated with significant morbidity and mortality. An elevated level of free T4 reflects the severity of AIT. In patients with significantly increased T4 values, an early surgical intervention should be considered.