Comparison of plasma oxidative biomarkers and conformational modifications of hemoglobin in patients with diabetes on hemodialysis

Background: Diabetes is associated with an increased generation of reactive oxygen species (ROS), which plays an important role in the development of oxidative stress and anemia.

Objectives: The main purpose of this study was to investigate whether patients with diabetes undergoing hemodialysis (HD) were susceptible to oxidative stress and whether resulting damages affect the structure of hemoglobin (Hb) and plasma proteins.

Patients and methods: Twenty patients with diabetes undergoing HD, 20 patients with diabetes and normal renal function, and 20 age- and sex-matched healthy subjects were included in this study. Methaemoglobin (Met-Hb), hemichrome and conformational changes of Hb were analyzed as oxidative markers in erythrocytes. Ferric reducing ability of plasma (FRAP) and protein carbonyl content (PCO) were determined as plasma oxidative biomarkers. Also triglyceride, cholesterol, albumin, blood urea nitrogen (BUN), creatinine, glucose and uric acid were assayed as biochemical parameters of plasma.

Results: Patients with diabetes undergoing hemodialysis had significantly lower levels of PCO and albumin (P < 0.05), but significantly higher levels of FRAP, BUN, creatinine and uric acid (P < 0.05) as compared to patients with diabetes and normal renal function. Linear regression analysis showed significant negative correlations between PCO and FRAP (r = -0.53), oxy-Hb (r = -0.88) and Hb absorbance at 340 nm (r = -0.79), 420 nm (r = -0.85) and 577 nm (r = -0.68) in patients with diabetes undergoing hemodialysis. Also PCO was significantly and positively correlated with Hb absorbance at 275 nm (r = 0.63) and 560 nm (r = 0.61) which confirmed the oxidative damage to erythrocytes in control subjects.

Conclusions: Hemodialysis exacerbates oxidative stress and conformational changes of Hb in patients with diabetes on hemodialysis. The FRAP value can be used as a positive determinant, while PCO and Hb derivatives can be used as negative determinants of oxidative stress in patients with diabetes.