[Subclinical hypothyroidism - laboratory finding or disease?].

Subclinical hypothyroidism first of all is a laboratory finding, defined by elevated TSH and normal peripheral thyroxine concentrations. The first steps are to verify the condition and to clarify whether the patient has underlying thyroid disease or other comorbidities. Results of recent studies on subclinical hypothyroidism are reassuring. No consistent association has been demonstrated between mildly elevated TSH levels (5-10 mIU / l) and cardiovascular events, mortality, fracture risk or cognitive impairment. In contrast TSH levels between 5-10 mIU / l may even confer lower mortality in the elderly and may hence be protective. These data strongly suggest that the long-time controversy on definition of normal upper TSH levels should take a more conservative turn. Thus, diagnosis of subclinical hypothyroidism should be handled cautiously. Individualized treatment decision is recommended if TSH levels are only mildly elevated and less than 8-10 mIU / l. In case of autoimmune thyroiditis or previous thyroid therapy (surgery, radioiodine treatment) the risk of progression to overt hypothyroidism has to be considered and there is no doubt that the latter should be avoided.