Hemoglobin and Plasma Vitamin C Levels in Patients on Peritoneal Dialysis

Abstract

Objective To determine the contribution of vitamin C (Vit C) status in relation to hemoglobin (Hb) levels in patients on long-term peritoneal dialysis (PD). Methods 56 stable PD patients were evaluated in a cross-sectional survey. Plasma samples were collected for Vit C (analyzed by HPLC with electrochemical detection) and high-sensitivity C-reactive protein (hs-CRP) determinations. Clinical records were reviewed for Hb, transferrin saturation (TSAT), ferritin, erythropoietin (EPO) dose, and other clinical parameters. Dietary Vit C intake was evaluated by patient survey and from patient records. Total Vit C removed during PD treatment was measured in 24-hour dialysate collections. Results Patients showed a highly skewed distribution of plasma Vit C levels, with 40% of patients below normal plasma Vit C levels (<30 μmol/L) and 9% at higher than normal levels (>80 μmol/L). Higher plasma Vit C levels were associated with higher Hb levels (Pearson r = 0.33, p < 0.004). No direct connection between Vit C levels and reported dietary intake could be established. In stepwise multiple regression, plasma Vit C remained significantly associated with Hb (p = 0.017) but there was no significant association with other variables (dialysis vintage, age, ferritin, TSAT, hs-CRP, residual renal function, and EPO dose). In 9 patients that were evaluated for Vit C in dialysate, plasma Vit C was positively associated (Spearman r = 0.85, p = 0.01) with the amount of Vit C removed during dialysis treatment. Conclusions These data indicate that plasma Vit C is positively associated with higher Hb level. Vit C status could play a major role in helping PD patients to utilize iron for erythropoiesis and achieve a better Hb response during anemia management.

Effect of peritoneal dialysis on antioxidant defense system and oxidative stress

“…5 Plasma vitamin C concentrations, unlike the lipophilic antioxidants were found to be markedly lower than in controls. Our findings are in accordance with the reports by Zhang 23 and Finkelstein et al, 24 but not with Mydlík et al 20 Low plasma concentration of vitamin C in dialysis patients can be due to inadequate intake of fruits and vegetables, loss during the dialysis process, reduced tubular reabsorption, impaired metabolism, and/or utilization of vitamin C in regenerating or sparing vitamin E from tocopheroxyl radicals. 11,22,23 In the present study, plasma levels of TAC were shown to be high in CAPD patients compared with the control group, similar to earlier studies.…”

Vitamins C and E: Beneficial effects from a mechanistic perspective

“…In addition to poor diet, alcoholism [56], elderly age, socioeconomic deprivation [57], mental illness [58], malabsorption disorders, kidney failure, hemodialysis [59], and peritoneal dialysis [60] have been identified as risk factors for low vitamin C status and developing clinical symptoms of scurvy [61-63]. In a geriatric hospital in Paris, France, 18 elderly patients (12%), who showed clinical symptoms of scurvy, had low serum levels of ascorbic acid compared to control patients (6.2 ± 6.0 μM versus 28 ± 24 μM, p < 0.001) [64].…”

Mortality Associated with Dose Response of Erythropoiesis-Stimulating Agents in Hemodialysis versus Peritoneal Dialysis Patients

“…In CKD patients, the ESA hyporesponsiveness may be related to chronic inflammation, iron deficiency and hyperparathyroidism, among other conditions [22,23,24,25,26]. The prevalence and predictors of these factors might be different between PD and HD patients, which may be reflected by the differences in received prescribed ESA dose between these two dialysis modalities [27].…”