Functional iron deficiency in patients on hemodialysis: prevalence, nutritional assessment, and biomarkers of oxidative stress and inflammation

Abstract Introduction: Anemic patients with chronic kidney disease (CKD) can be divided into anemic patients without or with functional iron deficiency (FID). The increase in the number of cases of hemosiderosis in patients on hemodialysis (HD) attributed to excessive intravenous iron replacement has called for the investigation of the factors involved in the genesis of FID. Objectives: This study aimed to describe the prevalence of FID in patients with CKD on HD, characterize the included individuals in terms of clinical and workup parameters, and assess their nutritional, oxidative stress, and inflammation statuses. This cross-sectional study assembled a convenience sample of 183 patients with CKD on HD treated in Southern Brazil. Patients meeting the inclusion and exclusion criteria were divided into two groups, one with anemic subjects with FID and one with anemic patients without FID. Participants answered a questionnaire probing into socio-epidemiological factors, underwent anthropometric measurements, and were tested for markers of anemia, oxidative stress, inflammation, and nutrition. Statistical analysis: The date sets were treated on software package GraphPad InStat version 3.1. Variables were tested with the Kolmogorov-Smirnov, chi-square, Student’s t, and Mann-Whitney tests. Statistical significance was attributed to differences with a p < 0.05. Results: Markers of inflammation were not statistically different between the two groups. Markers of anemia and nutrition were significantly lower in patients with FID. Patients with FID were prescribed higher doses of parenteral iron (p < 0,05). Discussion: FID was associated with lower nutritional marker levels, but not to increased levels of markers of inflammation or oxidative stress, as reported in the literature. Additional studies on the subject are needed.

摘要与引言：患有慢性肾脏病（chronic kidney disease, CKD）的贫血患者可分为无功能性铁缺乏（functional iron deficiency, FID）和伴功能性铁缺乏两类。因静脉铁剂补充过量导致血液透析（hemodialysis, HD）患者出现铁血黄素沉着症的病例数逐年上升，这促使学界针对功能性铁缺乏的致病相关因素展开探究。研究目标：本研究旨在描述血液透析慢性肾脏病患者中功能性铁缺乏的患病率，从临床与检验参数维度对纳入受试者进行特征刻画，并评估其营养、氧化应激及炎症状态。本横断面研究纳入巴西南部地区接受治疗的183名血液透析慢性肾脏病患者作为便利样本。符合纳入与排除标准的患者被分为两组：一组为合并功能性铁缺乏的贫血患者，另一组为无功能性铁缺乏的贫血患者。所有受试者填写了社会流行病学相关调查问卷，接受人体测量学指标检测，并完成贫血、氧化应激、炎症及营养相关标志物的检验。统计学分析：本研究数据采用GraphPad InStat 3.1版统计软件进行处理。变量分别通过柯尔莫哥洛夫-斯米尔诺夫检验（Kolmogorov-Smirnov test）、卡方检验（chi-square test）、学生t检验（Student’s t test）及曼-惠特尼检验（Mann-Whitney test）进行分析，以P<0.05作为差异具有统计学意义的判定标准。研究结果：两组患者的炎症标志物水平无统计学差异。合并功能性铁缺乏的患者，其贫血与营养相关标志物水平显著更低。该组患者的肠外铁剂处方剂量更高（P<0.05）。讨论：本研究发现，功能性铁缺乏与较低的营养标志物水平相关，但并未如既往文献报道那样与炎症或氧化应激标志物水平升高存在关联。该领域仍需开展更多相关研究。