Treatment guidelines for a mildly underactive thyroid gland – which affects up to one in then older men and women – are outdated, according to new research.
The study, published today in the New England Journal of Medicine and led by the University of Glasgow – in collaboration with colleagues from the Netherlands, Switzerland, Ireland and Denmark – shows that patients with a mildly underactive thyroid gland (subclinical hypothyroidism) are being prescribed an ineffective medicine.
Under current guidelines, the drug levothyroxine is prescribed to nine of every ten women with the condition and is the most prescribed drug in the US and the third most prescribed drug in the UK.
Subclinical hypothyroidism is a common contributor to many problems in older age, including causing non-specific symptoms such as tiredness or lethargy, muscle weakness, slowed thought processes, increased blood pressure and weight and circulation problems.
The five-year European study found that while levothyroxine tablets did effectively restore a normal balance of thyroid function, the treatment provided no apparent symptomatic benefits, with no improvement in muscle strength, speed of thought processes or any effect on body weight or blood pressure.
The authors are calling for a re-evaluation of the guidelines at a presentation at the Endocrine Society Meeting (ENDO 2017) today in Orlando, Florida.
Lead author Professor David Stott, the David Cargill Chair of Geriatric Medicine at the University of Glasgow's Institute of Cardiovascular and Medical Sciences, said: "Our aim is to significantly improve the health and well-being of older people with subclinical hypothyroidism, by resolving uncertainties about how best to manage this condition.
"Treatment with levothyroxine is common in clinical practice, but controversial. Our study concludes this treatment provides no apparent benefits for older adults and should therefore no longer be started routinely for this condition. An update of the guidelines is necessary."
The study followed 737 older adults (with an average age of 74 years). Half of the older adults in the trial were allocated to a placebo and half to levothyroxine, with participants followed up for at least a year.
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David J. Stott et al. Thyroid Hormone Therapy for Older Adults with Subclinical Hypothyroidism, New England Journal of Medicine (2017). DOI: 10.1056/NEJMoa1603825