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Should we treat subclinical hyperthyroidism?

Nature Clinical Practice Endocrinology & Metabolism volume 4, pages 550–551 (2008)Cite this article

Subclinical hyperthyroidism (i.e. low levels of serum TSH in association with normal serum T4 and T3 levels) is a common biochemical finding, with a prevalence of 1–10%. Cases are often iatrogenic and ∼25% of patients prescribed levothyroxine have low TSH levels, consistent with some degree of overtreatment. In addition, subclinical hyperthyroidism can reflect nonthyroidal illness or therapy with drugs such as glucocorticoids or dopamine, especially in hospitalized patients.

The first crucial step when evaluating a patient with subclinical hyperthyroidism is to consider the differential diagnosis and determine whether suppression of TSH reflects true thyroid autonomy as a result of early Graves' disease or, more commonly, the presence of autonomous nodules. The next step is to determine whether the biochemical abnormality is persistent. Many mild cases with low, but detectable, serum TSH values are transient—probably because they represent nonthyroidal illness or healthy outliers—and seldom progress to overt thyroid dysfunction. Although many patients who experience low TSH levels when taking levothyroxine have high-normal serum T4 values, their serum T3 concentrations are usually low-normal. By contrast, endogenous subclinical hyperthyroidism is characterized by T3 values towards the upper limit of normal and an altered T4 to T3 ratio. Concern has, therefore, focused on the potential harmful consequences of endogenous subclinical hyperthyroidism and, in turn, on the potential benefits of treatment.

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References

  1. Biondi B and Cooper DS (2008) The clinical significance of subclinical thyroid dysfunction. Endocr Rev 29: 76–131

    Article  CAS  Google Scholar 

  2. Sawin CT et al. (1994) Low serum thyrotropin concentrations as a risk factor for atrial fibrillation in older persons. N Engl J Med 331: 1249–1252

    Article  CAS  Google Scholar 

  3. Auer J et al. (2001) Subclinical hyperthyroidism as a risk factor for atrial fibrillation. Am Heart J 142: 838–842

    Article  CAS  Google Scholar 

  4. Cappola AR et al. (2006) Thyroid status, cardiovascular risk, and mortality in older adults. JAMA 295: 1033–1041

    Article  CAS  Google Scholar 

  5. Gammage MD et al. (2007) Association between serum free thyroxine concentration and atrial fibrillation. Arch Intern Med 167: 928–934

    Article  CAS  Google Scholar 

  6. Parle JV et al. (2001) Prediction of all-cause and cardiovascular mortality in elderly people from one low serum thyrotropin result: a 10-year cohort study. Lancet 358: 861–865

    Article  CAS  Google Scholar 

  7. Gussekloo J et al. (2004) Thyroid status, disability and cognitive function, and survival in old age. JAMA 292: 2591–2599

    Article  CAS  Google Scholar 

  8. Bauer DC et al. (2001) Risk for fracture in women with low serum levels of thyroid-stimulating hormone. Ann Intern Med 134: 561–568

    Article  CAS  Google Scholar 

  9. Sgarbi JA et al. (2003) The effects of early antithyroid therapy for endogenous subclinical hyperthyroidism in clinical and heart abnormalities. J Clin Endocrinol Metab 88: 1672–1677

    Article  CAS  Google Scholar 

  10. Surks MI et al. (2004) Subclinical thyroid disease: scientific review and guidelines for diagnosis and management. JAMA 291: 228–238.

    Article  CAS  Google Scholar 

Download references

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  1. 2nd Floor, Institute of Biomedical Research, The Medical School, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK j.a.franklyn@bham.ac.uk

Authors and Affiliations

  1. JA Franklyn is a Professor of Medicine at the University of Birmingham, Edgbaston, UK.,

    Jayne A Franklyn

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  1. Jayne A Franklyn
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Franklyn, J. Should we treat subclinical hyperthyroidism?. Nat Rev Endocrinol 4, 550–551 (2008). https://doi.org/10.1038/ncpendmet0917

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