Could a drug commonly prescribed to older people speed up bone loss?

• Levothyroxine is a commonly prescribed drug in the United States, especially in older adults, as decreased thyroid function may be associated with aging.
• However, questions remain about how well it is prescribed, as side effects can cause problems.
• A recent report presented at the annual meeting of the Radiological Society of North America suggests that use of levothyroxine in people with typical hormonal ranges may lead to decreased bone mass and density over time in older adults.

Levothyroxine, a drug used to treat hypothyroidism, may cause loss of bone mass and density in older people with normal thyroid levels, a small cohort study has found.

Researchers from Johns Hopkins University School of Medicine in Baltimore, Maryland, showed that total body mass and bone density decreased in adults over 65 years of age who received levothyroxine during a 6-year follow-up period.

The results came from a small study of 81 participants who had typical levels of thyrotropin, which is used to measure thyroid function, and who were taking levothyroxine.

The study authors note that levothyroxine is one of the most commonly prescribed drugs in the United States, especially among older adults.

Sean Ormond, MD, of Atlas Pain Specialists, who is dual board certified in anesthesiology and interventional pain management and was not involved in this study, said Medical news today What:

“Levothyroxine is a very common medication because the likelihood of developing thyroid problems increases with age. Older people are more prone to hypothyroidism, in which the thyroid gland slows down and does not produce enough hormones to keep the body functioning smoothly.”

“When the thyroid gland is not working well, people often feel tired, gain weight, get colds easily, or even become depressed. These symptoms can make life difficult, so doctors often prescribe levothyroxine to restore hormone levels and help people feel like themselves again. This is especially important in cases where untreated thyroid problems can harm the heart or other organs,” he further explained.

The thyroid gland is located in the neck and is responsible for the production of hormones, which in turn play a role in metabolism, the growth and development of children, temperature regulation, as well as the functioning of the heart and digestive system.

Thyroid-stimulating hormone (TSH) is produced by the pituitary gland, another hormone-producing organ in the head. This in turn causes the thyroid gland to produce T3 and T4, which play a role in the above processes.

Low thyroid hormone levels can lead to symptoms such as fatigue, weight gain, cold intolerance, dry, flaky skin, hair loss and inability to concentrate.

Conversely, hyperthyroidism, in which thyroid levels are too high, is associated with weight loss and muscle weakness, high heart rate and blood pressure, anxiety and irritability.

The team behind the recent study had previously shown that the use of levothyroxine, especially in people who use it unnecessarily, can have a number of unwanted side effects.

The authors previously showed that use of levothyroxine in people with higher thyroid hormone levels had a negative effect on leg weight in older adults, in a study whose results appeared in The Limits of Aging.

To examine the effects of taking levothyroxine in a similar group of adults, in their latest study, the authors looked at 32 men and 49 women who were 65 years or older at the start of the study, with a mean age of 73 years.

They matched these participants with five other cohort members on biological sex, body mass index (BMI), age, race, drinking history, smoking history, other treatments they had received, and TSH levels to create a quasi-control measure. group.

This cohort was analyzed after two visits at which they had their bone mass and density measured using dual-energy x-ray absorptiometry.

Researchers showed that in the study, those who had typical thyroid hormone levels and took levothyroxine demonstrated lower bone mass and density.

The results suggest that bone loss may be a consequence of levothyroxine use in older adults, even when used at appropriate dosages, which may be of concern in terms of the risk of osteoporosis.

Questions have been asked for some time about whether levothyroxine is being overprescribed in older people, and a letter was published in the journal. Clinical chemistry in 2023, suggesting that many people with hypothyroidism were diagnosed with hyperthyroidism.

It cites studies showing that TSH levels vary significantly throughout the year, peaking in the winter and declining in the summer months.

Hypothyroidism is diagnosed by looking at free thyroxine (T4) levels in people with elevated TSH levels and comparing their ratio.

People with high TSH and low T4 are diagnosed with hypothyroidism. People with slightly elevated TSH and slightly lower T4 are diagnosed with subclinical hypothyroidism, which can be treated with levothyroxine.

The letter suggested that by not taking into account normal seasonal fluctuations in TSH levels, many people are prescribed medications that may not help them and may even experience negative, avoidable side effects.

Not prescribing the drug is an option for patients who experience unpleasant side effects, said Sue Clenton, MD, consultant clinical oncologist at Weston Park Cancer Center in Sheffield, UK.

“Indications for levothyroxine include elevated TSH (indicating an underactive thyroid), fatigue, weight gain and slow cognitive function. However, deprescribing may be considered if the patient experiences side effects such as rapid heart rate, anxiety or bone loss, or if their thyroid function tests return to normal.”

She said the study highlighted “the importance of close monitoring and individualized treatment plans, especially in older adults.”