Common Thyroid Drugs Cause Bone Loss, New Research Finds

Hypothyroidism (underactive thyroid) can affect anyone, causing many unpleasant symptoms such as weight gain, fatigue, depression and hair loss, among other symptoms. . If left untreated, it can cause serious and life-threatening conditions. Fortunately, there are medications to treat the condition, and the most common method is hormone therapy like levothyroxine (better known by brand names like Synthroid). However, new research shows that this treatment may have unexpected effects in the form of bone loss.

RELATED: This Popular Supplement Could Be Bad For Your Bones—Here’s What You Should Avoid.

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A new study examined the possible relationship between levothyroxine use and bone loss in adults. According to a press release detailing the findings, approximately 23 million Americans, or 7 percent of the population, drink this supplement daily. The researchers also pointed out that some people have been taking these drugs for years, and it is not clear why they were first prescribed or whether they should still be taking them.

The researchers used data from the Baltimore Longitudinal Study of Aging (BLSA), which included information on “community-dwelling adults.” For the current study, researchers included participants who were 65 and older with at least two visits and thyroid tests that fell within normal reference ranges for thyroid-stimulating hormone. (TSH), defined as approximately 0.4 to 5.0 microunits per milliliter. (The reporter points out that “excess thyroid hormone,” known as hyperthyroidism, can lead to bone loss. This condition is called “osteoporosis.”

Overall, the study included 81 adults taking levothyroxine and 364 who were not. The participants had a mean age of 73, and all had TSH levels in the normal range of 2.35 at the first visit.

Patients included in the BLSA had multiple bone scans, providing “important information on bone development and bone changes over time, providing an understanding of prevalence of age-related osteoporosis,” study co-author. Eleanor SimonsickPhD, epidemiologist, and BLSA co-director, said in a press release.

After a mean follow-up of 6.3 years, older adults on levothyroxine experienced significant weight loss and bone mass loss.

RELATED: Weight-loss drugs can cause bone loss, research shows.

“Our study suggests that even when following current guidelines, levothyroxine use appears to be associated with significant bone loss in older adults,” Shadpour DemehriMD, senior author and professor of radiology at Johns Hopkins, said in the release. The new data will be presented at the annual meeting of the Radiological Society of North America (RSNA) next week in Chicago.

Some recent studies have also looked at levothyroxine, and the Yale School of Medicine estimates that as many as 90 percent of those taking the medication may not need it. Overuse of the treatment in adults over 80 can also have “serious side effects,” including death, Joe El-KhouryPhD, assistant professor of laboratory medicine, in a 2023 letter published in Clinical Chemistry.

Jennifer MomMD, PhD, co-author of the recent study and associate professor of endocrinology at Johns Hopkins, recommends that adults taking levothyroxine consult their doctor about their medications and get their thyroid checked. actively.

“A benefit-risk assessment should be done, to weigh the strength of the treatment against the possible negative effects of levothyroxine in this population,” Mammen said in the release.