Novel Approaches to the Diagnosis of Sarcopenia

Abstract

Sarcopenia is common in older people and is associated with disability, reduced mobility, hospitalization, and various comorbidities. Although it has been recognized for over a quarter of a century, we do not currently have a universally adopted definition. This limits our ability to compare results from different studies and impedes the development of novel therapies. Although sarcopenia was initially defined purely based on low muscle mass, the importance of measures of muscle function has been realized and these have been included in recent operational definitions. These continue to evolve with some including an assessment of adiposity and others adding further components of musculoskeletal health in a score-based approach. This review describes the importance of reaching a widely accepted method to define sarcopenia in both research and clinical practice. It details the ways in which the definition has changed since its initial inception and explores how it may continue to evolve in the future. The different methods by which components of sarcopenia can be measured are described, and the various advantages and disadvantages of these techniques are evaluated. Clearly, there are several other similar syndromes in older people, such as frailty and cachexia; their relationships and overlap with sarcopenia are also explored.

Sarcopenia and sarcopenic obesity

“…However, limited access, the high cost, and the risk of radiation (with CT) preclude the wider use of these techniques in clinical practice. Therefore, dual energy X-ray absorptiometry (DXA) is the preferred method for correctly evaluating body composition; it is widely used to assess muscle mass in research studies because of good precision and safety with relatively low radiation [7]. Therefore, measuring ALM using DXA has become a standard criterion in most current sarcopenia definitions.…”

“…Bioimpedance analysis (BIA) is an inexpensive, easy to use, and reproducible method that is considered a portable alternative to DXA. However, neither DXA nor BIA can distinguish between extracellular and intracellular water, making these techniques prone to error depending on the hydration status of the patient [7]. …”

“…Primary sarcopenia is the term used to define sarcopenia that is caused by aging itself, whereas secondary sarcopenia describes sarcopenia that is caused by disuse (immobility or physical inactivity), disease (advanced organ failure, malignancy, neurodegenerative, or endocrine diseases), and inadequate nutrition [6]. Sarcopenia is closely associated with frailty, physical disability, hospitalization, osteoporosis, osteoarthritis, and even mortality [7,8]. …”

Bioimpedance analysis vs. DEXA as a screening tool for osteosarcopenia in lean, overweight and obese Caucasian postmenopausal females

“…Interestingly, DEXA operating programs do not include automated results of skeletal muscle mass reports and thus do not provide sarcopenia values. 23 One should note that the formulas used in DEXA for sarcopenia estimation lack accuracy, as sarcopenia is an uneven condition, disturbing mainly postural muscles, while DEXA underestimates limb body mass by up to 20%. 41 Only one study used mathematical predictions of sarcopenia in a sample of an aged population.…”

“…Sarcopenia was defined by SM index calculations obtained by dividing appendicular SM evaluated by DEXA divided by body height squared (ASM/Ht 2 ), and the percentage of SM index (SMI%=total SM/body mass × 100) defining Class I sarcopenia in females as 19-24% and Class II sarcopenia as below 19% of total body weight. 14,23,24 The DEXA and BIA-ACC ® measurements were performed by the same two operators, respectively.…”