Levothyroxine, a widely prescribed medication in the United States for treating hypothyroidism, may be associated with decreased bone mass and density in older individuals with normal thyroid hormone levels, according to recent research findings. This medication is particularly prevalent among older adults, as thyroid function often declines with age.

A study presented at the Annual Meeting of the Radiological Society of North America revealed that the use of levothyroxine over a six-year period could contribute to reductions in both total body bone mass and density in adults aged 65 and older. The research conducted by a team from Johns Hopkins University School of Medicine involved a small cohort of 81 participants, all of whom had typical thyroid-stimulating hormone (TSH) levels indicative of normal thyroid function.

The authors of the study emphasize that while levothyroxine is essential for managing thyroid issues, especially in older populations prone to hypothyroidism, the medication's potential adverse effects warrant further investigation. Hypothyroidism can lead to symptoms such as fatigue, weight gain, cold sensitivity, and mood disturbances, prompting healthcare providers to prescribe levothyroxine to mitigate these issues and restore thyroid hormone levels.

The thyroid gland plays a crucial role in regulating metabolism, growth, and development, as well as maintaining the body's temperature and supporting heart and digestive functions. TSH, produced by the pituitary gland, stimulates the thyroid to produce hormones T3 and T4, which are essential for these bodily functions. Insufficient levels of these hormones can result in various health challenges, including fatigue and cognitive impairment.

Conversely, hyperthyroidism, characterized by excessive thyroid hormone levels, can lead to weight loss, muscle weakness, and heightened anxiety. The recent study raises questions about the appropriateness of levothyroxine prescriptions, particularly in cases where it may not be necessary. Previous research has indicated that levothyroxine could adversely affect muscle mass in older adults when used inappropriately.

The latest findings suggest a concerning trend: older adults taking levothyroxine, even at appropriate dosages, may face a heightened risk of osteoporosis due to bone density loss. This potential risk underscores the importance of careful monitoring and tailored treatment plans for older patients receiving thyroid medication.

There has been ongoing debate regarding the overprescription of levothyroxine, particularly among older adults. A letter published in Clinical Chemistry in 2023 highlighted concerns that hypothyroidism may be overdiagnosed, emphasizing the need to consider the natural variations in TSH levels throughout the year. Research indicates that TSH levels can fluctuate seasonally, which may lead to misdiagnosing individuals as hypothyroid and prescribing unnecessary medications.

Hypothyroidism is diagnosed based on elevated TSH levels alongside low free thyroxine (T4) levels. Patients exhibiting slightly elevated TSH and mildly low T4 levels may be classified as having subclinical hypothyroidism, often treated with levothyroxine. The aforementioned letter suggests that failing to account for seasonal TSH variations can result in unwarranted prescriptions of levothyroxine, potentially exposing patients to unnecessary side effects.

For patients experiencing adverse effects from levothyroxine, deprescribing may be a viable option. Medical professionals advise that treatment plans should be individualized, especially in older adults who may face complications from hormone therapy. Side effects such as rapid heart rate, anxiety, or bone loss should prompt reevaluation of the patient's medication regimen.

The recent study's findings highlight the necessity of ongoing research and careful assessment of levothyroxine usage in older populations. As the prevalence of hypothyroidism increases with age, it is critical to balance the benefits of thyroid medication with potential risks, ensuring that treatment remains safe and effective for all patients.