[Subclinical hyperthyroidism: from diagnosis to treatment].

Subclinical hyperthyroidism is a common clinical entity. Subclinical hyperthyroidism is defined as a serum TSH below the reference range but a normal T4 and T3 level in an asymptomatic patient. Whether or not subclinical hyperthyroidism should be treated remains a matter of debate. Cross-sectional studies and longitudinal population-based studies demonstrate association between subclinical hyperthyroidism and risk of atrial fibrillation, osteoporosis and cardiovascular and global mortality. However, there are no randomized clinical trials answering the question whether long term-health outcomes are improved by the treatment of subclinical hyperthyroidism. Therefore in the absence of evidence for or against treatment of subclinical hyperthyroidism, it seems appropriate to follow algorithms that consider the level of TSH and the presence of risks factors (age > 65 years, osteoporosis, post menopause and cardiac disease).