According to research published in Arthritis Research & Therapy, individuals undergoing levothyroxine treatment may have a higher likelihood of experiencing a decrease in quadricep muscle mass, which could potentially increase the risk of developing knee osteoarthritis (OA).
Dr. Mohajer and colleagues examined the data from the Osteoarthritis Initiative to investigate the relationship between levothyroxine and thigh muscle biomarkers in subjects at risk for developing knee OA. The experts analyzed 1043 matched thighs and knees, consisting of 266 levothyroxine users and 777 non-users. The results indicated that levothyroxine use was associated with a reduction in quadriceps cross-sectional areas (CSAs) (mean difference, 95% CI: -16.06 mm2/year, -26.70 to -5.41), while it did not impact the composition of the thigh muscles. Furthermore, levothyroxine usage was linked to a higher 8-year risk of both radiographic and symptomatic knee OA incidence (hazard ratio (HR), 95% CI: 1.78, 1.15-2.75). Finally, mediation analysis revealed that the decrease in quadriceps mass (i.e., CSA) partially contributed to the increased risk of knee OA incidence associated with levothyroxine use.
A 2012 study revealed significant muscle impairments in patients with knee osteoarthritis (OA). Compared to age-matched controls, individuals with knee OA exhibited impairments in the quadriceps, hamstrings, and hip muscles. Muscle strength, particularly in the quadriceps, has a profound impact on performance-based physical function and self-reported physical function. However, it remains uncertain whether stronger quadriceps can help prevent the development and progression of knee OA.
Experts recommend incorporating exercise therapy, including global and targeted resistance training, to help reduce pain and improve function in patients with knee OA. Moreover, since levothyroxine is commonly prescribed for underactive thyroid gland conditions, it is essential to consider the underlying thyroid function as a potential confounder or effect modifier when interpreting the study findings. Future research is also required to investigate the indicators of thyroid function that underlie the longitudinal alterations in the thigh muscles.
References
- Mohajer B, Moradi K, Guermazi A, Mammen JS, Hunter DJ, Roemer FW, Demehri S. Levothyroxine use and longitudinal changes in thigh muscles in at-risk participants for knee osteoarthritis: preliminary analysis from Osteoarthritis Initiative cohort. Arthritis Research & Therapy. 2023 Dec;25(1):1-1.
- Alnahdi AH, Zeni JA, Snyder-Mackler L. Muscle impairments in patients with knee osteoarthritis. Sports health. 2012 Jul;4(4):284-92.