One of the most common prescription medications could put you at higher risk of losing bone density, according to new research.
About 23 million Americans take levothyroxine, also known by the brand name Synthroid, every day, making it the second most used drug among older adults in the United States.
It is prescribed for people who have thyroid problems, a butterfly-shaped gland in the neck that controls energy, weight and hair growth. Hypothyroidism affects approximately one in 20 Americans over the age of 12.
Previous research has found that having too much thyroid hormone in the body increases the risk of bone fracture. Knowing this, researchers at Johns Hopkins investigated the effect that taking levothyroxine had on bone health.
By studying dozens of people over six years, they found that people taking the drug were more likely to lose a greater amount of bone tissue than people not taking the drug.
Professor Shadpour Demehri, a radiology expert at Johns Hopkins University in Maryland and co-author of the study, said: “Our study suggests that even following current guidelines, levothyroxine use appears to be associated with greater bone loss in older adults.” .
Low bone density can make someone more fragile and prone to bone fractures, a condition known as osteoporosis.
Levothyroxine, pills that cost just a few pence a day to combat the disease, could increase the risk of losing bone mass and bone density.
The thyroid is a gland in the neck that releases chemicals that control metabolism and energy.
In the study, researchers evaluated 81 patients who were taking levothyroxine and 364 who were not taking it, with an average age of 73 years and a thyroid-stimulating hormone level of 2.35.
The research will be presented in full at the annual meeting of the Radiological Society of North America next week in Chicago.
Normal levels are usually 0.4 to 4.0 milliunits per liter (mU/L).
During a six-year follow-up, they found that those taking levothyroxine suffered “greater loss of bone mass and total body bone density.”
Patients taking the drug who had a “normal” level of thyroid-stimulating hormone also suffered loss of bone mass and density, the researchers added.
Dr. Jennifer Mammen, study co-author and associate professor of endocrinology at Johns Hopkins, said adults taking levothyroxine should discuss their treatment with a doctor and periodically monitor their thyroid function tests.
He said: “A risk-benefit assessment should be undertaken, weighing the strength of the treatment indications against the potential adverse effects of levothyroxine in this population.”
This could also suggest that Synthroid is being overprescribed, said Dr. Elena Ghotbi, lead author of the study and a postdoctoral researcher at John Hopkins University.
Dr Ghotbi said: “The data indicate that a significant proportion of thyroid hormone prescriptions can be given to older adults without hypothyroidism.
This is not the first article to critically analyze the drug. According to 2023 research from Yale School of Medicine, about 90 percent of people taking the drug may not need it.
Dr Joe El-Khoury, professor of laboratory medicine, who led the research, said: “Study after study has shown that there is an increased risk when overtreating levothyroxine in patients who may not need it.”
This x-ray shows a woman with a hip fracture, which is one of the most debilitating fractures associated with osteoporosis, according to Yale. Thyroid problems are much more common in women than in men.
The Johns Hopkins researchers did not specifically study osteoporosis, but low bone density is a precursor to this condition, which affects approximately 10 million people over the age of 50.
In osteoporosis, the holes inside the bone widen and cause the outer walls of the bone to thin, becoming brittle and easily breakable.
Then, if someone has a small fall, they may be at risk for major bone fractures, including hip fractures.
According to Yale School of Medicine, these hip fractures can cause someone to lose mobility and independence and have been linked to earlier death.
Osteoporosis becomes much more common with age, but the chances of developing the condition increase if someone smokes, has a poor diet, has arthritis, or bone cancer.
Additionally, hormones play a role in bone health. This includes thyroid hormones, sex hormones such as estrogen and testosterone, and growth hormones such as insulin.
Women are five to eight times more likely to develop thyroid problems than men.
It’s unclear what causes these disorders, but if left untreated, they can cause heart disease and infertility, according to the American Thyroid Association.