J LI1,2, K MCNICHOLAS1,2, K TORPEY1, L THORBURN1, C DELANEY3, A ROWLAND4, J GLEADLE1,2
1Dept of Renal Medicine, Flinders Medical Centre, Sturt Road, Bedford Park, Australia, 2College of Medicine and Public Health, Flinders University, Bedford Park, Australia, 3Dept of Vascular Surgery, Flinders Medical Centre, Sturt Road, Bedford Park, Australia, 4Dept of Clinical Pharmacology, Flinders University, Bedford Park, Australia
Aim: It was reported that light exposure caused red blood cell lysis over 90 years ago. The mechanism of such lysis and the clinical consequences are unclear. The effects of prolonged light exposure on the blood of haemodialysis patients are uncertain. We tested the hypothesis that light exposure during haemodialysis leads to haemolysis and increased levels of oxidative stress markers in blood.
Background: During haemodialysis, a patient’s entire blood volume traverses a transparent circuit of tubing every 20 mins. Given 3 haemodialysis sessions a week, a patient’s blood is exposed to ambient light up to 50 times in a week. This raises the concern whether the light exposure may increase haemolysis and contribute to oxidative stress. We measured the levels of free haemoglobin and the oxidative stress marker, F2-isoprostane (15-F2t-IsoP) in patients’ blood in conventional versus light-shielded haemodialysis.
Methods: In a cross-over trial spanning 2 weeks, we took bloods from 32 patients pre and post dialysis. Each patient had one week of conventional haemodialysis alternating with one week of light-shielded haemodialysis in which all extracorporeal circuitry was covered to prevent light exposure of blood. Plasma 15-F2t-IsoP was measured by competitive ELISA and free haemoglobin measured as a marker of haemolysis.
Results: Free haemoglobin levels did not change significantly (p=0.32) in patient bloods undergoing conventional dialysis (0.01 pg/mL) compared to light-shielded dialysis (-0.01 pg/mL). The mean concentration of 15-F2t-IsoP in conventional dialysis patient plasma (3,613 pg/mL) was not significantly different from light-shielded dialysis (3,223 pg/mL) (p=0.316).
Conclusions:Haemolysis as judged by free haemoglobin was not increased in conventional haemodialysis versus light-shielded nor did exposure to light increase the plasma level of oxidative stress marker, 15-F2t-IsoP.
Bio to be advised