Protein turnover in malnourished elderly subjects: the effects of refeeding.

A primed constant-rate infusion of L-(l-14C)-leucine was used to assess protein flux, synthesis, and breakdown in a group of malnourished elderly subjects (n = 9) and a group of age-matched healthy elderly control subjects (n = 9). No significant differences between the two groups were observed in measures of protein metabolism. Four out of six malnourished subjects, restudied after a period of dietary replenishment, showed non-significant increases in protein synthesis and breakdown. Plasma insulin concentrations were significantly suppressed (p less than 0.05) and plasma growth hormone and cortisol concentrations significantly elevated (p less than 0.05) in the malnourished subjects before and after refeeding compared with the healthy elderly controls.