Plasma glutathione peroxidase deficiency caused by renal dysfunction

Area of Science:

• Biochemistry
• Nephrology
• Clinical Chemistry

Background:

• Glutathione peroxidase (GPx) is a key antioxidant enzyme.
• Renal failure can impact various biochemical markers.
• The role of GPx in chronic renal failure (CRF) requires further elucidation.

Purpose of the Study:

• To investigate plasma and erythrocyte glutathione peroxidase (GPx) activity in patients with chronic renal failure (CRF).
• To assess the relationship between GPx activity and renal function markers.
• To compare GPx levels in patients undergoing different dialysis modalities.

Main Methods:

• Plasma and erythrocyte GPx activity assays were performed.
• Immunoblot analysis was used to detect plasma GPx protein levels.
• Serum creatinine was measured as a marker of renal function.
• Patients included healthy controls, nondialyzed CRF patients, hemodialysis (HD) patients, and continuous ambulatory peritoneal dialysis (CAPD) patients.

Main Results:

• Plasma GPx activity showed a significant negative correlation with serum creatinine in nondialyzed CRF patients (r = -0.71).
• Reduced or undetectable plasma GPx protein was observed in patients with low plasma GPx activity.
• Plasma GPx activity was significantly reduced in both HD and CAPD patients compared to controls, with greater reduction in females.
• Erythrocyte GPx activity remained unchanged across all patient groups.

Conclusions:

• Plasma GPx activity is significantly dependent on renal function.
• Reduced plasma GPx levels in CRF patients are likely due to impaired renal clearance or synthesis, not selenium deficiency.
• Cellular GPx activity is preserved, indicating a specific impact on extracellular GPx in renal failure.