Effect Of Calcium And Phosphorus Metabolism On Oxidative Stress In Maintenance Hemodialysis Patients

Objective:We investigate the correlation of calcium and phosphorus metabolism with oxidative stress in maintenance hemodialysis patient, and observe whether lowering phosphorus ameliorate the oxidative stress.Methods:60 MHD patients from Blood Purification Center of the Fourth Affiliated Hospital of Guangxi Medical University, aged 20-60 years, who received hemodialysis 3 times per week,4 hours each time.60 normal people from health examination center were selected as control. Patients' general information, gender, age, body mass index and dialysis age were collected. Fasting blood samples were collected before hemodialysis for detection of calcium?phosphorus, SOD, MDA (TBARS method), AOPP(colorimetry). The correlation between oxidative stress and calcium, phosphorus, calcium phosphorus product and PTH were analyzed respectively. MHD patients were divided into Group A (?1.78mmol/L) and group B (> 1.78mmol/L) according to phosphorus level, and MDA, AOPP, SOD levels were compared. Stepwise mutiple regression analysis was used to observe the important factor that affects oxidative stress.33 MHD patients whose phosphorus>1.78mmol/L were received lowering phosphorus treatment for 3 months and phosphorus, SOD, MDA, AOPP were detected.Results:The MDA and AOPP of MHD patients were significantly higher than that of normal control (P<0.01), while SOD was significantly lower (P<0.01). The MDA and AOPP levels in Group B patients was significantly higher than that of Group A [(7.81±2.59 mmol/L) vs. (6.31±2.19 mmol/L) and (179.12±36.84?mol/L) vs. (159.32±38.48?mol/L) respectively, P<0.05], while the SOD level was significantly lower than that of the later [(71.83±27.13 U/ml) vs. (90.44±24.04 U/ml), P<0.05]. SOD was negatively correlated with phosphorus, while MDA and AOPP were positively correlated (r=-0.323,0.296, 0.314 respectively, and P=0.012,0.022,0.014 respectively). SOD was negatively correlated with calcium-phosphorus product, while MDA and AOPP were positively correlated (r=-0.273,0.263,0.276 respectively, and P=0.035, 0.042,0.033 respectively). SOD, MDA, AOPP have no significant correlation with calcium (P=0.398,0.603,0.450 respectively). SOD was negatively correlated with PTH, while MDA and AOPP were positively correlated (r=-0.312,0.265,0.257 respectively, and P=0.015,0.041,0.047 respectively). After lowering phosphorus treatment for 3 months, blood phosphorus decreased significantly [(2.41±0.51 mmol/L) vs. (2.01±0.63 mmol/L), P=0.003], while SOD increased from (71.83±27.12) U/L to (82.44±19.51) U/L (P=0.039), and MDA, AOPP decreased from (7.81±2.59) mmol/L and (179.12±36.84) u mol/L to (6.26±1.62) mmol/L and (152.68±28.42)?mol/L respectively (P=0.011,0.004 respectively).Conclusions:There was abnormal oxidative stress in MHD patients. The oxidative stress was significantly correlated with phosphorus, calcium-phosphorus product and PTH in MHD patients, and not with calcium level. Lowering phosphorus treatment ameliorates oxidative stress in MHD patients.