Should we pay more attention to low creatinine levels?

A review is made of the basic aspects of creatine/creatinine metabolism and the close relationship between creatinine and muscle mass, which makes the former a biochemical marker of the latter. Emphasis is placed on the current prognostic value of both the low urinary excretion of creatinine and low serum creatinine levels in different clinical settings in which sarcopenia probably plays a significant role in morbidity and mortality.