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）患者患有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素。虽然炎症可能导致PEM，但低膳食蛋白质摄入量（DPI）通常是一个促成因素。MHD患者的DPI通常约为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，通常是用过时的透析治疗类型进行的。该项目有两个主要目标：研究1。评估临床稳定的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.检验以下假设：在临床稳定的PEM MHD患者中，DPI为1.30 g/kg/d（而非1.00 g/kg/d）治疗5个月与无尿素总体内氮（TBNuf）显著增加相关。在研究1中，将在临床研究中心对9例患者进行研究，同时以随机顺序喂食以下5种DPI，每种持续17天：0.60、0.80、1.00、1.15和1.30 g/kg/天。每名患者的能量摄入将基于其间接热量测定。关键的结果指标是氮平衡。我们将评估这些DPI对禁食和进食期间全身（13 C-亮氨酸）蛋白质合成和降解以及13 C-亮氨酸氧化、血浆氨基酸、透析液氨基酸、肽和蛋白质以及身体组成（人体测量法、双X射线光子吸收测定法（DXA））的影响。我们将试图更精确地定义尿素氮外观（UNA），蛋白氮外观（PNA）和DPI之间的关系，并探讨尿素动力学方程估计UNA，PNA，DPI和尿素池的有效性。在研究2中，将70名MHD门诊患者随机分配至DPI为1.00或1.30 g/kg/天的组，各持续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和近红外线相互作用，通过TBNuf、体细胞质量（TBK）和身体组成的其他组分评估全身蛋白质。

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.