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UK NICE guideline favors levothyroxine, radioactive iodine therapy for thyroid disorders
Physicians who treat patients with hypothyroidism should opt for levothyroxine monotherapy in most patients, and when treating patients with Graves’ disease, radioactive iodine is the optimal treatment option, according to a summary of new National Institute for Health and Care Excellence, or NICE, guidelines published in The BMJ.
“There are two types of reviews that we do for NICE guidelines,” Kristien Boelaert, MD, PhD, FRCP, head of the Institute of Metabolism and Systems Research and a Reader in Endocrinology at the University of Birmingham, U.K., told Healio. “One is the clinical evidence review and then one is the health economic evidence review. Recommendations are made based on a combination of clinical effectiveness and then cost-effectiveness.”
‘A cascading approach’
To identify patients who need treatment, physicians must test thyroid-stimulating hormone (thyrotropin) levels, which should be done in “a cascading approach,” according to the guideline. This cascading approach requires an initial test of TSH. If this testing indicates raised levels, then the guideline recommends an assessment of free thyroxine with an assessment of free T4 and free triiodothyronine necessary only when TSH is below the reference range. The guideline also emphasizes the importance of taking one blood sample and using it throughout this battery of tests.
“We recommend that that is done on the same sample so that we don’t keep repeating samples on patients. We don’t ask them to come back for a further test, which is a discomfort for the patient and is costly,” Boelaert said. “You start it from TSH, and then depending on the result, you then cascade further to measure either free T4, and if that’s normal, then you may need to measure free T3.”
Levothyroxine over liothyronine
When hypothyroidism is detected, the guideline urges the use of levothyroxine treatment alone and recommends that physicians do not routinely prescribe liothyronine, even when combined with levothyroxine therapy, and advises against prescription of natural thyroid extract.
“There was no clinical benefit from giving T3 alone or in combination,” Boelaert said of liothyronine. “When you then combine that with something that’s significantly more expensive, then that is not something that can be recommended routinely by the guideline.”
Levothyroxine should not be dosed at the same amount for all patients; however, with patients younger than 65 years requiring 1.6 µg/kg of body weight per day while older patients require a daily starting dose of 25 µg to 50 µg, that should be adjusted as needed, according to the guideline.
“What we recommend for hypothyroidism is that for most patients this is treated with levothyroxine replacement,” Boelaert said. “We don’t routinely recommend prescription of liothyronine either in combination or alone for patients, and we recommend against natural thyroid extract for the treatment of hypothyroidism.”
A slightly altered path should be taken when patients present with subclinical hypothyroidism. A tipping point of 10 TSH mU/L determines which route to take. Patients with a measure of 10 mU/L or more require levothyroxine treatment outright while patients with a measure of less than 10 mU/L, but only those younger than 65 years, should take levothyroxine on a trial basis for 6 months if they have symptoms of hypothyroidism.
“For subclinical hypothyroidism, what we recommend is that if serum TSH is above 10 mU/L, that patients are treated regardless of age,” Boelaert said. “If it’s above the reference range but below 10 mU/L, then for people under 65, we recommend a trial of treatment if they have symptoms. The evidence showed that there was no benefit, so we don’t recommend it for patients over 65 with subclinical hypothyroidism and a TSH that’s lower than 10 mU/L.”
Radioactive iodine therapy stands above
Testing for thyrotoxicosis, hyperthyroidism and Graves’ disease should also be conducted. To determine whether Graves’ disease is present, TSH receptor antibodies should be assessed, according to the guideline. If Graves’ disease is diagnosed, then radioactive iodine therapy is the preferred treatment option.
“This is very much based on a review of the clinical and the cost-effectiveness evidence. We found that this was clinically, a very effective treatment and more effective than antithyroid drugs,” Boelaert said. “I think many other guidelines will recommend it as a first-line treatment for toxic nodular disease. That is not controversial. That’s already a recommendation that most guidelines make.”
The new guideline will continue to evolve as research develops. Of particularly interest is more examinations of the combination of T4 and T3, radioactive iodine and antithyroid medications, among others, Boelaert said.
“Our first research recommendation of the guideline is that we need more evidence on T4 or T4/T3 combination and then a further sub-question to that is whether there are certain patient groups that would particularly benefit from having combination therapy. That was our resounding main recommendation, which will be important to do further research on,” Boelaert said. “There is a further research recommendation that’s lower down on the list looking at iodine and selenium for subclinical hypothyroidism.” – by Phil Neuffer
For more information:
Kristien Boelaert, MD, PhD, FRCP, can be reached at k.boelaert@bham.ac.uk.
Disclosure: Boelaert reports no relevant financial disclosures.
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