Updated guidance from NHS England on treating hypothyroidism warns liothyronine should only be initiated by a consultant endocrinologist and patients taking it should be reviewed be a specialist if they have not been already.
It follows a joint position statement from the British Thyroid Association and Society for Endocrinology which concluded patients can be considered for a trial liothyronine but only in certain circumstances.
Under the recommendations, combined liothyronine and levothyroxine can be prescribed by a specialist in the small minority of patients with persistent symptoms, as long as the diagnosis has been confirmed, co-morbidities ruled out as the cause and levothyroxine dose optimised.
Once treatment is stable, this can be passed to the GP but only if they are willing to take over the prescribing it adds.
The NHS England advice for prescribers, which links to the joint statement also sets out liothyronine treatment should be withdrawn if not working.
It comes amidst ongoing regional variation in the use of liothyronine and conflicting guidance which experts say has put NHS clinicians in a difficult position.
Despite 20 years of debate, the issue remains controversial, the joint statement says, with trials showing no evidence of benefit.
Currently there is a 49-fold variation in prescriptions for liothyronine as a proportion of treatment between regions in the UK, it notes.
Some areas had banned its use due to dramatic price hikes but more recently liothyronine cost has come down. It remains 50-fold more expensive than equivalent levothyroxine monotherapy.
The cost of liothyronine increased by almost 6,000% in a decade – from £4.46 in 2007 to £258.19 by July 2017, as revealed in an investigation by the Competition and Markets Authority.
It was recently announced that the CMA ruling had been upheld after an appeal and the £84m fine for Advanz’s excessive pricing will stand.
NICE guidelines do not recommend routine use of liothyronine either alone or in combination.
Clinicians are told it can be prescribed in ‘exceptional circumstances’ but this is unhelpful given many patients with persistent symptoms would likely put themselves in this category putting pressure on doctors to prescribe.
‘This has put NHS clinicians in a difficult situation. While neither NICE nor [the Regional Medicines Optimisation Committee] support routine liothyronine use, both leave the possibility open to some patients,’ the statement concludes.
The BTF/SfE state that doctors are not obliged to prescribe any medication that they believe is not in the patient’s best interest.
‘In particular, doctors have no obligation to continue to provide NHS prescriptions for liothyronine that have been started by another medical practitioner (including private practice), or when purchased independently of medical advice or supervision from an online or overseas pharmacy,’ it adds.
‘Many endocrinologists may not agree that a trial of liothyronine/levothyroxine combination therapy is warranted in these circumstances and their clinical judgement is valid given the current understanding of the science and evidence of the treatments.’
It adds that online surveys show most patients continue to have persistent symptoms after liothyronine use and in that case, it is reasonable to stop its use.
‘Given limited efficacy and long-term safety data around use of liothyronine, long term prescription should be reserved for a very select group of patients with evidence of sustained response to combination therapy,’ the statement concludes.
However, both levothyroxine and liothyronine are currently overprescribed including in patients with transient elevation in TSH and those with persistent subclinical hypothyroidism, the joint statement says.
Professor Simon Pearce, professor of endocrinology at Newcastle University and co-author of the position statement, said all the evidence suggests that liothyronine makes no difference.
‘This is why this is so controversial because where patients do feel well on a treatment, there is little rationale to stop it.
‘If the results found in trials of [liothyronine] had been found for a cancer drug that drug would be dead in the water. But there may be a small number of patients who feel it makes a difference.’