Techniques for the diagnosis of sarcopenia

Abstract

SummarySarcopenia is an age-related process of skeletal muscle loss associated with declining physical performance, highly prevalent among older subjects, with a negative prognostic effect on falls, disability and mortality risk. Modern approaches to sarcopenia case finding and diagnosis are based on physical performance measures, while assessment of muscle mass represents the second diagnostic step. Muscle mass can be quantified at different levels of body composition, with a complexity increasing from atomic detection to anatomic measure. In the choice of measuring method, different factors have to be taken into account, including validity, simplicity, cost and specific purpose (clinical versus research). Some methods, such as MRI and CT, have high validity but are complex and costly. Bioelectrical impedance analysis is inexpensive and easy to perform in most settings, being the preferred method for clinical practice. Dual energy X-ray absorptiometry has intermediate cost and complexity with good reproducibility, and is more reliable for research setting. Other methods, such as administration of tritium (D3)-marked creatine and measurement of urinary D3-creatinine, are still in a preclinical phase of development. For all methods the issue of normative data does exist and needs to be solved, in order to reliably identify homogeneous populations with sarcopenia, to be targeted in clinical practice and intervention studies.

Sarcopenia and its individual criteria are associated, in part, with mortality among patients on hemodialysis

“…Although previous epidemiologic studies 20, 21 in hemodialysis patients have reported that higher muscle mass, representing by higher quartile of mid-arm muscle circumference, was significantly associated with greater survival, those studies analyzed the data by using arbitrary cutpoints for high muscle mass derived from within their cohort rather than cutpoints derived from normative data from young, healthy individuals as recommended in the definition of sarcopenia. 2, 3, 11 In addition, reliance on anthropometric measures in those studies could lead to misclassification because of interobserver variation 22 and fatty infiltration of muscle compartments that occurs with atrophy. 23 Isoyama and colleagues 10 also recently found that patients new to dialysis with low muscle mass (defined as appendicular muscle mass by DXA/height 2 at least 2 SDs below the sex-specific mean of young adults) were not at higher risk of mortality.…”

Association of Appendicular Lean Mass, and Subcutaneous and Visceral Adipose Tissue With Mortality in Older Brazilians: The São Paulo Ageing & Health Study

“…An assessment of whole‐body composition by DXA has been increasingly used both in clinical and research practice because it provides an optimal combination of accuracy, cost, and safety. It is acknowledged by many practitioners as the most accurate method for estimating body composition in clinical practice …”

Characterization of body composition and definition of sarcopenia in patients with alcoholic cirrhosis: A computed tomography based study

“…The more recent methods like bioelectrical impedance analysis (BIA), dual energy x‐ray absorptiometry (DEXA) and air displacement plethismography are recognized as the indirect methods of assessing body composition in particular the muscle mass . In recent times, computed tomography (CT) has emerged as a more sensitive and specific measure of assessing both adiposity and muscle mass . Hence, this study was planned to characterize the body composition in patients with alcoholic cirrhosis using a precise gold standard method of computed tomography and also to define sarcopenia based on the carefully derived cut‐offs from healthy controls.…”