Dietary Protein Requirements in Hemodialysis Patients

描述（由申请人提供）：高比例的维持性血液透析（MHD）患者存在蛋白质-能量营养不良（PEM），这是高发病率和死亡率的有力预测因子。虽然炎症可能导致PEM，但低饮食蛋白质摄入（DPI）通常是一个促成因素。MHD患者通常的DPI约为1.0 g蛋白质/kg/天，而专家组建议= 1.20 g蛋白质/kg/天。然而，这些建议是基于很少的研究，通常持续时间不足，这些研究通常是对过时的透析治疗类型进行的。这个项目有两个主要目的：研究1。评估临床稳定型MHD患者的膳食蛋白质需求。假设维持氮平衡的平均DPI为1.00 g蛋白质/kg/天，但几乎所有MHD患者维持平衡的安全摄入量约为1.25 g蛋白质/kg/天。研究2。为了验证以下假设：在临床稳定的MHD合并PEM患者中，DPI为1.30 g/kg/天而非1.00 g/kg/天的治疗5个月与无尿素总氮（TBNuf）显著增加相关。在研究1中，9例患者将在临床研究中心进行研究，并随机喂食以下5种dpi，分别为0.60、0.80、1.00、1.15和1.30 g/kg/d，每17天。每个病人的能量摄入将基于他们的间接量热法。衡量结果的关键指标是氮平衡。我们将评估这些dpi在禁食和饲养期间对全身（13c -亮氨酸）蛋白质合成和降解以及13c -亮氨酸氧化的影响，血浆氨基酸，透析液氨基酸，肽和蛋白质，以及身体成分（人体测量，双x射线光子吸收测定法（DXA））。我们将尝试更精确地定义尿素氮外观（UNA），蛋白质氮外观（PNA）和DPI之间的关系，并研究尿素动力学方程用于估计UNA， PNA， DPI和尿素池的有效性。在研究2中，70名MHD门诊患者将被随机分配到DPI为1.00或1.30 g/kg/天的组，每个组持续5个月，使用饮食咨询和食物补充剂。在这5个月之前和之后，将使用人体测量、DXA和近红外相互作用，通过TBNuf、体细胞质量（TBK）和其他身体成分来评估总蛋白。

DESCRIPTION (provided by applicant): A high proportion of maintenance hemodialysis (MHD) patients have protein-energy malnutrition (PEM), which is a powerful predictor of high morbidity and mortality. Although inflammation may contribute to PEM, low dietary protein intake (DPI) is often a contributing factor. The usual DPI of MHD patients is about 1.0 g protein/kg/day, whereas expert groups recommend = 1.20 g protein/kg/day. However, these recommendations are based upon few studies, often of insufficient duration, that were usually carried out with obsolete types of dialysis therapy. This project has two primary aims: Study 1. To assess dietary protein requirements in clinically stable MHD patients. It is hypothesized that the average DPI that will maintain nitrogen balance is 1.00 g protein/kg/day, but that a safe intake that maintains balance in almost all MHD patients is about 1.25 g protein/kg/day. Study 2. To test the hypothesis that in clinically stable MHD patients with PEM, treatment for 5 months with a DPI of 1.30 g/kg/day, but not 1.00 g/kg/day, is associated with a significant increase in urea-free total body nitrogen (TBNuf). In Study 1, 9 patients will be studied in a clinical research center while they are fed, in random order, the following 5 DPIs, each for 17 days: 0.60, 0.80, 1.00, 1.15 and 1.30 g/kg/day. Energy intake for each patient will be based on their indirect calorimetry. The key outcome measure is nitrogen balance. We will assess the effects of these DPIs on total body (13C-leucine) protein synthesis and degradation and 13C-leucine oxidation during fasting and feeding, plasma amino acids, dialysate amino acids, peptides and proteins, and body composition (anthropometry, dual x-ray photon absorptiometry (DXA)). We will attempt to define more precisely the relationships between urea nitrogen appearance (UNA), protein nitrogen appearance (PNA) and DPI and investigate the validity of urea kinetic equations for estimating UNA, PNA, DPI and urea pools. In Study 2, 70 MHD outpatients will be randomly assigned to a DPI of 1.00 or 1.30 g/kg/day for 5 months each, utilizing dietary counseling and food supplements. Before and after these 5 months, total body protein will be assessed by TBNuf, body cell mass (TBK), and other components of body composition using anthropometry, DXA, and near infra-red interactance.