If you've been diagnosed with mildly low thyroid function and you're an older adult, you may not get symptom relief from the commonly prescribed medication, according to new research.
It's routine that people diagnosed with mildly low thyroid function, which doctors call subclinical hypothyroidism, are prescribed levothyroxine (Synthroid, Levoxyl, others). However, a new study that evaluated more than 700 adults, all over age 65 (and on average age 74) finds that the medication did not have a consistent beneficial effect on their thyroid-related symptoms such as fatigue and tiredness.1
While prescribing the medication is routine, ''what this study suggests is, that's not really evidence-based practice'' in older adults, says study co-investigator Douglas Bauer, MD, professor of medicine, epidemiology and biostatistics at the University of California San Francisco School of Medicine.
Guidelines about how to treat the condition should be updated, says the study's leader, David Stott, MD, the Cargill chair of geriatric medicine at the University of Glasgow, in a press release. "Our study concludes this treatment provides no apparent benefits for older adults and should therefore no longer be started routinely for this condition,'' Dr. Stott writes.
However, other experts not involved in the study say this research is not the last word and that more study, with longer follow up, is needed.
The researchers randomly assigned about half of the more than 700 adults to get the medication and the other half to get a placebo pill. Neither group knew which they were taking. Those on the active medication took 50 ug a day, or if they weighed less than 110 pounds, half that dose.
Subclinical hypothyroidism involves mildly elevated levels of thyroid stimulating hormone (TSH) and normal blood levels of the hormones T3 and T4. If TSH is too high, it means your thyroid gland is failing.2
While the treatment with levothyroxine did restore thyroid function back to normal, there weren't improvements in symptoms such as tiredness. Nor was there improvement in muscle strength, speed of thinking, healthier weight or blood pressure, all of which have been linked with low thyroid problems.
The study is published Apr. 3 in the New England Journal of Medicine. The researchers also presented it at ENDO 2017, the annual meeting of the Endocrine Society, in Orlando.
Some patients in this age group may still ask their doctors for the medication, says Angela M. Leung, MD, MSc, assistant professor of medicine at the UCLA David Geffen School of medicine and an endocrinologist at UCLA Health, Santa Monica.
That was her takeaway after reading through the study, which she was not a part of. "It is conceivable that some subclinically hypothyroid patients may still be in favor of at least a trial of low dose thyroid hormone replacement," she says.
Even though the study did not find a consistent effect on symptom relief, "I would think that at least some doctors would agree that there is little harm in doing so," Dr. Leung says.
Future studies in this age group may shed more light on the issue, she tells EndocrineWeb. "I think research will continue to evolve on this topic," she says.
Treating mildly underactive thyroid is a challenge, Dr. Leung says, because there is a wide array of symptoms that could be attributed to the condition but could stem from other causes as well.
The study is certainly not the ''last word," agrees J. Michael Gonzalez-Campoy, MD, PhD, FACE, medical director and CEO of the Minnesota Center for Obesity, Metabolism and Endocrinology in Eagan, Mn., and an editorial board member of EndocrineWeb.
The study's main follow up was just 12 months, for one thing, Dr. Gonzalez-Campoy says. And there is a possibility that having low thyroid activity for many years may affect levels of cholesterol and cardiovascular risk, he says. And that may tip the scale towards treatment.
Thyroid hormones control your metabolism. When thyroid hormones levels are low and levels of thyroid stimulating hormone (TSH), which regulates the thyroid gland, is high, your cholesterol can rise, in turn increasing the risk of heart disease.
Dr. Bauer suggests that older patients with low thyroid function and their doctors might explore the possibility that the symptoms of fatigue and tiredness may stem from other causes, such as lack of exercise, lack of sleep or medication side effects.
He suggests older patients with mildly low thyroid function talk to their doctors about starting or resuming an exercise program, getting adequate sleep, or making other positive lifestyle changes. Improvements in those habits may make a difference in symptoms, he says.
backup about thyroid and cholesterol…