Thyroid hormones should not be routinely offered to adults with a mildly underactive thyroid gland, according to a panel of international experts.
Writing in The BMJ*, the panel strongly recommends against hormone treatment for subclinical hypothyroidism based on new evidence that it does not improve quality of life or symptoms including low mood and fatigue.
Their advice is part of The BMJ’s ‘Rapid Recommendations’ initiative - to produce rapid and trustworthy guidance based on new evidence to help doctors make better decisions with their patients.
Subclinical hypothyroidism (SCH) affects up to about 5% of the adult population, but 10-15% of the elderly. While some people have no symptoms at all, others can show mild signs of fatigue, low mood and weight gain, which may or may not be related to the condition.
Subclinical hypothyroidism can only be detected by a blood test. In the UK, about 25% of adults have thyroid function tests every year and guidelines tend to recommend hormones for those with TSH levels above 10 mIU/L (a normal TSH level is 0.4 to 4.0 mIU/L).
Research shows that hormone treatment for SCH has doubled from 1996 to 2006.
So an international panel of clinicians and patients with SCH used a recent detailed analysis of the latest evidence (a systematic review of 21 trials and about 2,200 participants comparing the effects of thyroid hormone treatment with no treatment or placebo in adults with SCH) to develop recommendations for clinical practice.
Using the GRADE approach (a system used to assess the quality of evidence), the panel makes a strong recommendation against thyroid hormones for almost all adults with SCH, because there were no benefits from treatment on fatigue, low mood, weight gain or any other outcomes that were tested.
What’s more, they say taking a pill and attending lifelong check-ups is burdensome, and they cannot rule out the possibility of harms.
And while they did not take costs and resources into account beyond direct costs to patients, they say thyroid hormones cannot be cost effective.
The recommendation does not apply to women who are trying to become pregnant or patients with particularly high TSH levels (above 20 mIU/L). It may also not apply to patients with severe symptoms or some aged under 30.
Future research could explore whether there is an unidentified group of patients who might benefit from treatment, say the authors.
In the meantime, if implemented, this recommendation “may substantially alter prescribing trends” they conclude.
Responding to the findings, Professor Helen Stokes-Lampard, Chair of the Royal College of General Practitioners, said: "Prescribing is a core skill for GPs and we will always aim to take into account the physical, psychological and social factors potentially affecting a patient before recommending any form of medication – as well as taking into account relevant clinical guidelines.
"Thyroid hormones are powerful drugs and GPs will only ever prescribe them if we think they are of genuine benefit to the person sitting in front of us, particularly as it usually means taking the tablets and being monitored in the long-term. If evidence shows that they are not going to be of benefit to our patients, it is important that we know this and that it is reflected in the clinical guidelines that inform our decision-making.
"The authors make a powerful case based on emerging evidence, and it is important that this new research is taken on board as clinical guidelines are updated and developed, in the best interests of our patients. It is also important that patients do not suddenly stop taking their thyroxine medication, but that they discuss this with their GP at their next routine medication review."
*Bekkering G E, Agoritsas T, Lytvyn L, et al. Thyroid hormones treatment for subclinical hypothyroidism: a clinical practice guideline BMJ 2019; 365 :l2006