Myopenia: A Significant Factor in Muscle Loss for Rheumatoid Arthritis Patients

Rheumatoid arthritis (RA), a chronic autoimmune disorder affecting individuals of various ages and genders, has long been recognized for its detrimental effects on joint health. Recent studies, however, have unveiled a lesser-known yet critical aspect of the disease: myopenia, a specific form of muscle loss that significantly contributes to the overall decline in musculoskeletal health in RA patients.

According to Professor Jiake Xu from the School of Biomedical Sciences at The University of Western Australia, myopenia is distinct from other muscle-wasting conditions, such as cancer cachexia and heart failure, as it involves a reduction in muscle mass without corresponding fat loss. This condition can emerge in patients of any age, differentiating it from typical age-related muscle deterioration. The findings of Professor Xu and his team were published on June 16, 2025, in the journal *Bone Research*.

The importance of understanding myopenia lies in its potential to serve as an early clinical marker for RA onset. Professor Xu states, "The intersection of myopenia and accelerated musculoskeletal ageing in RA represents a multifaceted area of research, highlighting both the urgency and potential for optimizing patient outcomes through targeted care."

Myopenia has profound implications for patient health, as it leads to significant muscle loss that adversely affects functional capacity and increases the risk of frailty and mortality. The research team notes that patients with RA experience more severe reductions in muscle mass compared to their healthy peers, making myopenia a potential indicator of early, disease-related muscular ageing.

In their comprehensive review, the researchers delineate the two overlapping conditions associated with muscle loss in RA: myopenia and secondary sarcopenia. While primary sarcopenia is linked to the natural aging process, secondary sarcopenia arises from the effects of illness or its treatment. Myopenia, however, is characterized by muscle loss independent of age, and researchers have found that it often follows a non-linear trajectory of decline, contrasting sharply with the gradual loss typical of age-related sarcopenia.

The study highlights the genetic and environmental factors contributing to myopenia in RA, including chronic inflammation, oxidative stress, and hormonal imbalances. Importantly, the clinical characteristics of myopenia can vary based on the age of RA onset. In elderly-onset rheumatoid arthritis (EORA), for instance, muscle mass may already be diminished due to normal aging, which can exacerbate the effects of myopenia. Conversely, young-onset rheumatoid arthritis (YORA) patients may start with higher muscle mass, but prolonged inflammation can gradually impair their muscular function.

"EORA patients experience muscle mass reduction that further weakens their physical capacity," explains Professor Xu. Understanding these age-specific differences is crucial for developing effective interventions aimed at preserving muscle mass in RA patients.

The review also emphasizes the diagnostic and therapeutic relevance of myopenia in RA management. Early detection of this condition could facilitate timely interventions that may include tailored exercise regimens, nutritional support, and pharmacological treatments designed to alleviate muscle loss and reduce associated frailty risks.

As Professor Xu concludes, "Early detection of myopenia combined with a comprehensive management strategy may enhance the quality of life and physical independence for individuals living with rheumatoid arthritis."

This emerging focus on myopenia underscores the need for continued research into the mechanisms underlying muscle loss in RA, as well as the development of targeted therapies that address this critical aspect of patient care. With further investigation, the insights gained from studying myopenia could significantly improve health outcomes for RA patients, allowing them to maintain better overall function and quality of life.