GDF11 and sarcopenia: Aging process is accelerated in uremia, and aging-related organ derangements, including sarcopenia, cardiac hypertrophy, and impaired cognitive function, are more prevalent in uremic patients.12,13 Therefore, to clarify the pathophysiological role of GDF11 in humans, it is interesting to examine whether circulating levels of GDF11 are decreased or increased in uremic subjects.