Myopenia—a new universal term for muscle wasting

A universal term describing the presence of clinically relevant muscle wasting that warrants medical intervention is required. The term sarcopenia might be used in this context. However, common use now means that sarcopenia is more often regarded as synonymous with age-associated muscle wasting in the elderly. We suggest the term "myopenia" to indicate the presence of clinically relevant muscle wasting due to any illness and at any age. This term would translate well into any language and is sufficiently specific if appropriately defined. We suggest to define myopenia as a clinically relevant degree of muscle wasting that is associated either with impaired functional capacity and/or with increased risk of morbidity or mortality. The precise cut-points to define myopenia may be different in various diseases. Myopenia could be diagnosed when a certain degree of muscle wasting over time has occurred (for instance, at least 5% in 6-12 months) or when muscle mass is below a certain threshold level (for instance, the <5th centile of healthy 30-year-olds or a fat-free mass index <16 kg/m(2) for men and <15 kg/m(2) for women). Future studies need to refine these in a disease-specific manner and link them to degrees of functional impairment that are clinically relevant and/or to degrees of risk of morbid or fatal events.