A recent study presented at the Radiological Society of North America meeting suggests that the common medication for hypothyroidism, levothyroxine, could be linked to bone loss in older adults. Levothyroxine, also known under brand names like Synthroid, is a synthetic form of thyroxine, a hormone produced by the thyroid gland. It’s widely prescribed, especially among older adults, with about 23 million Americans—7% of the population—taking it daily.
Levothyroxine is used to treat hypothyroidism, where the thyroid doesn’t produce enough thyroxine, leading to symptoms like weight gain, fatigue, and hair loss. However, excess thyroxine is linked to bone fractures. Even when thyroid levels remain normal, the study found that older adults taking levothyroxine daily for about six years experienced more significant bone loss.
The research involved participants aged 65 or older, including 81 who were taking levothyroxine and 364 who were not. All had normal thyroid hormone levels confirmed through blood tests and underwent bone density scans. After six years, those on levothyroxine showed greater loss in bone mass and density, particularly as thyroxine levels increased.
While the study noted a connection between levothyroxine and bone loss, it did not establish a definitive cause. Other factors might contribute to bone loss in those taking the medication. Generally, there isn’t conclusive evidence that levothyroxine causes bone loss in patients with normal thyroid levels.
Experts like Aaron Schulman, MD, caution against stopping levothyroxine based on this study alone, as many patients rely on it for health reasons. It remains the most trusted treatment for an underactive thyroid, despite potential concerns about bone health. Other treatments could pose even higher risks of bone loss, especially in older adults.
Schulman and others recommend consulting with a doctor if there are concerns about levothyroxine. It’s crucial to ensure the diagnosis of hypothyroidism is accurate since some people with normal hormone levels might take the medication for related symptoms. Adjusting the dose rather than stopping the medication might be a better approach to managing thyroid hormone levels and minimizing bone health risks.
