筋萎縮＝サルコペニアではない

筋萎縮は必ずしもサルコペニアではないというレビュー論文を紹介します。

Hepple RT.　Muscle atrophy is not always sarcopenia.　J Appl Physiol. 2012 Apr 19. [Epub ahead of print]

サルコペニアはもともと加齢により筋肉量低下を意味する言葉として最初に定義されました。しかし最近では、がん悪液質など加齢以外の原因も含めた筋萎縮にサルコペニアという言葉が使われています。

加齢による筋萎縮は他の原因による筋萎縮（特にがん悪液質）とは異なるので、サルコペニアという用語を加齢以外の筋萎縮に使用するのは不当であり、混乱の原因となっているとのことです。

老年医学の立場から言えばごもっともだと思います。ただすべての原因、すべての年齢による筋萎縮を意味するミオペニアという言葉は、まだほとんど普及していません。そのため、狭義の老年医学のサルコペニア、広義のリハ栄養のサルコペニアと言わざるをえないのが現状です。

Abstract
Sarcopenia is a term originally coined in reference to the decline of muscle mass with aging. However, in recent times this term is being used operationally in many clinical disciplines (e.g., cancer cachexia) to define a level of muscle atrophy independent of aging per se. It is argued here that aging muscle is distinct from several other forms of muscle atrophy, particularly cancer cachexia, and therefore that use of the term sarcopenia in these non-aging contexts is unwarranted and likely to cause confusion in the field. This argument is made based upon the established histopathology of aging muscle showing it to exhibit characteristic features of muscle afflicted by repeating cycles of denervation and reinnervation. It is argued that these and other histological features should be used to distinguish sarcopenia from other clinical conditions associated with muscle atrophy and to objectively justify return of the term sarcopenia to use in the aging field exclusively. Furthermore, the histopathological features of aging muscle should be more rigorously employed to refine our search for the mechanisms of sarcopenia and its successful treatment.