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Ep 35 – Subclinical hyperthyroidism in primary care


Posted 9 Nov 2021

Dr Kevin Fernando

In this episode, Dr Kevin Fernando discusses diagnostic and management tips – as well as pitfalls to avoid – related to subclinical hyperthyroidism. Fatima is a 71-year-old woman who presents in primary care with non-specific malaise and a past medical history of atrial fibrillation, ischaemic heart disease and osteoporosis. On examination, there is no evidence of thyroid swelling. Her blood tests reveal a suppressed thyroid-stimulating hormone (TSH), but normal free thyroxine (FT4) and free triiodothyronine (FT3). Given Fatima's comorbidities, what should we do next?


Key references discussed in the episode:

Key take-home messages from the episode:

  • Subclinical hyperthyroidism is diagnosed when thyroid-stimulating hormone (TSH) is suppressed below the normal reference range, but free thryoxine (FT4) and free triiodothyronine (FT3) concentrations are within the normal reference range.
  • Affects 5% of those aged >60 years.
  • More than 50% of cases of isolated low TSH with normal free hormones will return to normal with no treatment.
  • Causes include Grave’s disease, toxic thyroid nodules, thyroiditis and non-thyroidal illness. Iatrogenic causes include steroids, amiodarone, dopamine agonists, cancer immunotherapies and antiretrovirals.
  • Main concern with subclinical hyperthyroidism is potential exacerbation of conditions such as atrial fibrillation, ischaemic heart disease and osteoporosis.
    • If any of these conditions present, discuss with endocrinology for consideration of treatment.

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