Guidance in Subclinical Hyperthyroidism and Subclinical Hypothyroidism: Are We Making Progress?

Abstract

'Subclinical' Is a Misnomer and Should Be Replaced by a Grading System SHyper and SHypo are misnomers because the term 'subclinical' suggests the absence of symptoms and signs of thyroid hormone excess or deficiency, respectively. Such symptoms and signs, however, can sometimes be present, e.g. atrial fibrillation is a well-known manifestation of thyrotoxicosis and its prevalence is increased in SHyper [5]. Also, subjects with SHypo score slightly higher than controls on a clinical scale for hypothyroid-ism [6]. The confusing term 'subclinical' should thus better be avoided [7] , and a more accurate terminology is required. SHyper and SHypo are defined exclusively by biochemical criteria (TSH outside but FT 4 and FT 3 within their respective reference ranges). Evered et al. [8] proposed 40 years ago to grade hypothyroidism along biochemical criteria. They distinguished between grade I (subclinical), grade II (mild), and grade III (overt) hy-pothyroidism (table 1) [8]. TSH becomes progressively higher and FT 4 progressively lower in the transition from grade I to grade III. The grading system of Evered et al. has not been adopted by the medical community, but in my view has lost none of its attractiveness. It might The ETA guidelines on subclinical hyperthyroidism (SHyper) in the present issue of European Thyroid Journal [1] , together with the previously published ETA guidelines on subclinical hypothyroidism (SHypo) [2, 3] , offer up-to-date recommendations on the management of subjects with subclinical thyroid dysfunction. Guidance in this field is most welcome because of continuing uncertainty whether or not therapeutic intervention will improve health outcomes. Although the evidence of associations between SHyper or SHypo and adverse health outcomes has become much stronger in the last decade, evidence is lacking that restoration of the euthyroid state reverses the risk of adverse health outcomes. There are no long-term randomized clinical trials demonstrating that treatment will do more good than harm [4]. Against this background, one may wonder whether the grades of evidence attached to some of the recommendations are not overrated. Nevertheless, the guidelines could be very helpful in making treatment decisions. In this editorial, however, I would like to explore the question if we are really making progress in our thoughts about SHyper and SHypo. In other words, which topics have not been addressed by the present guidelines? Are there less prominent but still clinically relevant issues?