Abstract: Purpose To explore the relationship between the serum concentration of vitamin C (VC) and parameter values reflecting the Mineral and Bone Disorder (MBD) in Maintenance hemodialysis (MHD) patients. Method This study employs a pre-post self-comparison design. 92 patients were selected and divided into two groups based on the level of the serum VC concentration at the beginning of the study: a normal-VC group (VC＞=4mg/L, the control group) and a deficient-VC group (VC＜4mg/L, the intervention group). At the same times, all patients’intact Parathyroid hormone (iPTH), Alkaline Phosphatase (ALP), Calcium (Ca),
Phosphate (P), and Ca×P were examined and recorded at the beginning of the study. During the study, the intervention group was given an injection of 300mg vitamin C at the end of each dialysis, while the normal group got no treatment. The patients were monitored for 3 months and then examined again on the serum concentration of VC, iPTH, ALP, Ca, P and Ca×P at the end of the observation period. The data was analyzed with SPSS 19.0. Results ①VC deficiency was common in the MHD patients (78.3%). There was a significant difference in the base serum vitamin C level between the normal-VC group and the deficient-VC group [5.644(2.200) vs.1.312(1.940) mg/L，Z=- 6.895，P＜0.001], as well as in the serum iPTH [99.00(230.72)vs. 206.30(315.10)pg/ml，Z=-1.049，P=0.029] and ALP [82.00(42.50)vs.123.00(234.00)U/L, Z=-2.367，P=0.018]. ②After the three-month observation period: ① The serum VC concentration of the control group was reduced than before, but the difference was not statistically significant (5.64(4.29，6.49) vs. 5.11 (3.94，6,15)P=0.057). The VC concentration of the intervention group was statistically significantly increased (mg/L ，(1.31(0.80，2.02) vs. 4.59(2.46，5.70)，P＜0.001). ②The serum MBD indicators: the serum iPTH, ALP, P, and Ca×P of the patients in the control group were increased, but none of the difference was statistically significant. The intervention group showed statistically significant reduce in serum iPTH [206.30(133.40，428.50) vs.154.00(76.50, 388.00)pg/mL, Z= - 2.207 ，P<0.001] and serum ALP [123.00(78.00，312.00) vs. 95.00(60.00，140.00) U/L, Z=-3.749，P=0.011]. The Serum Ca, P, and Ca×P were also slightly lower than before, but the differences were
not statistically significant. 3. The Pearson/Spearman correlation coefficients, as well as the coefficients of the linear regressions suggested that there was a negative correlation between the plasma vitamin C level and ALP level of the MHD patients(B=-8.538, P=0.014). Conclusion Vitamin C deficiency is a common phenomenon in MHD patients. Regular dialysis can cause the loss of vitamin C. Providing supplementary Vitamin C to MHD patients can reduce the level of iPTH and ALP. There is a negative correlation between the plasma vitaminC level and ALP level. The deficiency of Vitamin C in MHD patients may be correlated with MBD.

Key words: Maintenance hemodialysis (MHD), Vitamin C (VC), Mineral and Bone Disorder (MBD)