Study finds levothyroxine use in older adults linked to increased bone loss

According to a recent study unveiled by SciTechDaily, levothyroxine use in older adults may be linked to an increased risk of bone loss, even when thyroid-stimulating hormone (TSH) levels are within the normal range. 

This underscores the importance of regular monitoring and personalized treatment to ensure the benefits outweigh the potential risks.

Levothyroxine, the second most commonly prescribed medication for older adults in the US, may be linked to bone loss, according to research presented at the recent Radiological Society of North America (RSNA) annual meeting.

Levothyroxine, sold under various brand names such as Synthroid, is a synthetic version of the hormone thyroxine and is primarily prescribed to treat hypothyroidism (underactive thyroid). In individuals with hypothyroidism, the thyroid fails to produce enough thyroxine, leading to symptoms like fatigue, weight gain, and hair loss. If left untreated, hypothyroidism can cause serious health complications.

Around 23 million Americans, or approximately 7 per cent of the population, take levothyroxine daily. In some cases, patients have been on this medication for years, but it remains unclear whether it was initially prescribed due to hypothyroidism or if it is still necessary.

Lead author Elena Ghotbi, M.D., a postdoctoral research fellow at Johns Hopkins University School of Medicine, pointed out that “data suggests a significant number of thyroid hormone prescriptions may be given to older adults without hypothyroidism, raising concerns about potential excess thyroid hormone levels even when treatment targets reference range goals.” 

While thyroid-stimulating hormone (TSH) levels typically range from 0.4 to 5.0 microunits per milliliter, excess thyroid hormone has been linked to an increased risk of bone fractures.

In this study, a collaborative effort between the Russell H. Morgan Department of Radiology and Radiological Science and the Endocrinology Department at Johns Hopkins Medical Institutions, Dr. Ghotbi and her team sought to investigate whether the use of levothyroxine and elevated thyroid hormone levels within the normal reference range are linked to increased bone loss over time in older adults with normal thyroid function, also known as "euthyroid" adults.

The researchers utilized data from the Baltimore Longitudinal Study of Aging (BLSA), a long-term observational cohort study of older adults living in the community. Dr. Ghotbi's study focused on participants aged 65 and older who had undergone at least two visits and had thyroid function tests consistently within the normal reference ranges.

By Naila Huseynova