Should we treat mild subclinical/mild hyperthyroidism? Yes.

Whether or not subclinical hyperthyroidism (SCH) should be treated, remains a matter of debate because there are no randomized clinical trials answering the question if treatment improves long-term health outcomes. Cross-sectional and longitudinal population-based sudies demonstrate clear associations between SCH and risk on atrial fibrillation and fractures; associations with cardiovascular and overall mortality and mental health are less consistent. Associations with adverse outcomes of cardiovascular and bone health are in all likelihood causally related to SCH in view of an observed dose-response relationship and the existence of a plausible biologic mechanism. Short-term intervention studies show improvement of surrogate outcome measurements. Against this background treatment of both endogenous and exogenous SCH is recommended when TSH is 0.1 mU/l or lower. At TSH values>0.1-<0.4 mU/l treatment should be considered in the presence of risk factors (age>65 years, post menopause, osteoporosis, cardiac disease).