Sultana Tanjim, DeVita Maria V, Michelis Michael F
Division of Nephrology, Lenox Hill Hospital, New York, NY, USA.
Int Urol Nephrol. 2016 Sep;48(9):1519-24. doi: 10.1007/s11255-016-1309-9. Epub 2016 May 11.
Functional iron deficiency (FID) is a major cause of persistent anemia in dialysis patients and also contributes to a suboptimal response to erythropoietin (Epo) administration. Vitamin C acts as an enzyme cofactor and enhances mobilization of the ferrous form of iron to transferrin thus increasing its bioavailability. High-dose intravenous vitamin C has been shown to decrease the Epo requirement and improve hemoglobin levels in previous studies. This study assessed the effect of low-dose oral vitamin C on possible reduction in Epo dose requirements in stable hemodialysis patients with FID.
This prospective study included 22 stable hemodialysis patients with FID defined as transferrin saturation (T sat) <30 % and ferritin levels of >100 mcg/L with Epo requirement of ≥4000 U/HD session. Patients received oral vitamin C 250 mg daily for 3 months. Hemoglobin, iron and T sat levels were recorded monthly. No one received iron supplementation during the study period.
There was a significant reduction in median Epo dose requirement in the 15 patients who completed the study, from 203.1 U/kg/week (95 % CI 188.4-270.6) to 172.8 U/kg/week (95 % CI 160.2-214.8), (P = 0.01). In the seven responders, there was 33 % reduction in Epo dose from their baseline. Despite adjustment of Epo dose, the mean hemoglobin level was significantly increased from 10.1 ± 0.6 to 10.7 ± 0.6 mg/dL (P = 0.03). No adverse effects of oral vitamin C were observed.
Daily low-dose oral vitamin C supplementation reduced Epo dose requirements in hemodialysis patients with FID. Limitations of this study include a small sample size and the lack of measurements of vitamin C and oxalate levels. Despite concerns regarding oral vitamin C absorption in dialysis patients, this study indicates vitamin C was well tolerated by all participants without reported adverse effect.
功能性缺铁（FID）是透析患者持续性贫血的主要原因，也是促红细胞生成素（Epo）治疗反应欠佳的原因之一。维生素C作为一种酶辅因子，可增强亚铁形式的铁向转铁蛋白的转运，从而提高其生物利用度。既往研究表明，高剂量静脉注射维生素C可降低Epo需求量并提高血红蛋白水平。本研究评估了低剂量口服维生素C对稳定的FID血液透析患者Epo剂量需求可能的降低作用。
这项前瞻性研究纳入了22例稳定的FID血液透析患者，其定义为转铁蛋白饱和度（T sat）<30%，铁蛋白水平>100 mcg/L，每次血液透析（HD）疗程的Epo需求量≥4000 U。患者每天口服250 mg维生素C，持续3个月。每月记录血红蛋白、铁和T sat水平。研究期间无人接受铁补充剂。
完成研究的15例患者的Epo剂量需求中位数显著降低，从203.1 U/kg/周（95%CI 188.4 - 270.6）降至172.8 U/kg/周（95%CI 160.2 - 214.8），（P = 0.01）。在7例有反应者中，Epo剂量较基线降低了33%。尽管调整了Epo剂量，但平均血红蛋白水平仍显著从10.1±0.6 mg/dL升至10.7±0.6 mg/dL（P = 0.03）。未观察到口服维生素C的不良反应。
每日低剂量口服补充维生素C可降低FID血液透析患者的Epo剂量需求。本研究的局限性包括样本量小以及未测量维生素C和草酸盐水平。尽管对透析患者口服维生素C的吸收存在担忧，但本研究表明所有参与者对维生素C耐受性良好，未报告不良反应。
