The Dilemma of Treating Subclinical Hypothyroidism: Risk that Current Guidelines Do More Harm than Good.

surement of both serum thyroid-stimulating hormone (TSH) and free thyroxine along with thyroid peroxidase antibodies after a 2to 3-month interval. We agree that repeating thyroid function tests is important as many patients will normalise their TSH results and should not be treated with levothyroxine. Some will show progression to overt biochemical hypothyroidism where treatment is no doubt warranted. However, the usefulness of autoantibodies in supporting the decision whether to start thyroxine is less clear, since although antibody-positive subjects have an increased risk of developing biochemical hypothyroidism over a prolonged follow-up [2] , the decision whether to treat is based on thyroid function status and symptoms rather than on the presence of auto-antibodies. After repeat thyroid function tests, the ETA guideline then recommends that when TSH is persistently elevated, patients should be categorised by TSH level (mild increase 4.0–10.0 mU/l, severer increase >10 mU/l) and by age (<70 years categorised as ‘younger’ and over 80 or 85 years as ‘oldest old’). It is stated that ‘age-specific local reference ranges for serum TSH should be considered in order to establish a diagnosis of SCH in older people’ [1]. We Dear Editor, The recent European Thyroid Association (ETA) guideline on the treatment of subclinical hypothyroidism (SCH) [1] will potentially be widely used by clinicians faced with this common condition. Although the report includes much useful background and guidance, we suggest that the approach recommended there carries potential risks, with the likely outcome of an increase in the proportion of ‘younger’ elderly patients treated for SCH and the withholding of thyroxine treatment in the very elderly, in the absence of any good evidence that this will give net clinical gain. We suggest that the current uncertain state of evidence merits a very simple approach and that watchful waiting with repeat thyroid function tests is the appropriate strategy for most patients with persisting subclinical hypothyroidism. The exception to this are patients with biochemical SCH who have one or more symptoms that cannot be explained otherwise, particularly tiredness or fatigue, affecting quality of life and expected to improve with thyroid hormone replacement. Such patients may not be truly ‘subclinical’ and a ‘trial’ of thyroxine treatment is warranted, as suggested in the ETA guidelines. When biochemical SCH is identified, the ETA guideline suggests a repeat meaReceived: January 27, 2014 Accepted: February 14, 2014 Published online: June 11, 2014