Plasma glutathione peroxidase activity in the elderly

Schiavon et al. (1994) have reported that the measurement of plasma glutathione peroxidase activity (PGP) could provide an index of renal function. Its activity, which was depressed in patients with impaired renal function, correlated positively with creatinine clearance and negatively with serum creatinine. To evaluate the hypothesis that the plasma PGP activity may be used to assess renal function in elderly, we measured the plasma PGP and creatinine clearance (ClCr) in 65 active, community-dwelling elderly (range: 65-93 years; 47 women and 18 men). We did not include persons with advanced renal failure in our study. PGP did not correlate with PCr and it was similar among patients with normal and with increased PCr (127.0 ± 30.7 U/l and 119.7 ± 21.6 U/l, respectively). A positive correlation was found between PGP and ClCr (r = 0.30; p < 0.01). Plasma PGP activity was lower in patients with a ClCr lower than 70 ml/min/1.73 m² than in those who had a higher ClCr (113.0 ± 25.8 U/l and 131.2 ± 26.7 U/l, p < 0.01). However, no correlation was found between ClCr and PGP in subjects with lower ClCr. PGP did not correlate with age but there was a correlation between ClCr and age (r = -0.24, p < 0.05). Our results suggest that plasma PGP activity is decreased in the patients with impaired renal function but this decrease does not correlate with age-dependent decline of kidney function.