McKee A, Morley JE, Matsumoto AM, Vinik A. Sarcopenia: an Endocrine Disorder? Endocr Pract. http://journals.aace.com/doi/10.4158/EP171795.RA?code=aace-site Sarcopenia is defined as low muscle function (walking speed or grip strength) in the presence of low muscle mass. A simple screening test - the SARC-F - is available to identify persons with sarcopenia. The major endocrine causes of sarcopenia are diabetes mellitus and male hypogonadism. Other causes are decreased physical activity, loss of motor neuron units, weight loss, inflammatory cytokines, reduced blood flow to muscles, very low 25(OH) vitamin D levels and decreased growth hormone and igf-1. Treatment for sarcopenia includes resistance and aerobic exercise, leucine enriched essential amino acids, and vitamin D. In hypogonadal males, testosterone improves muscle mass, strength and function. Selective androgen receptor molecules and antimyostatin activin II receptor molecules are under development as possible treatments for sarcopenia.