Brändle E, Sieberth H G, Hautmann R E
Department of Urology, University of Ulm, Germany.
Eur J Clin Nutr. 1996 Nov;50(11):734-40.
Relatively little is known about the influence of chronic oral protein intake on the kidney function. In most studies only the effect of a short-term change in protein intake [6-28 days] or the effect of an acute protein load on the glomerular filtration rate was studied. The purpose of this study was to investigate the effect of chronic oral protein intake on endogenous creatinine clearance and on the albumin excretion rate.
In a prospective study 88 healthy volunteers with normal renal function (32 vegetarians, 12 body-builders with no supplementary protein concentrates, 28 body-builders with supplementary protein concentrates and 16 subjects with no special diet) were examined. In order to investigate the effect of chronic oral protein intake, the participants were on their diet for at least 4 months.
Endogenous creatinine clearance as a measure for glomerular filtration rate varied between 32 ml/min and 197 ml/min or 34 and 186 ml/min x 1.73 m2, respectively. Nitrogen excretion rate was used as a measure for the daily protein intake, since it is known to correlate linearly with the daily protein intake. Nitrogen excretion rates ranged between 2.66 g/d and 33.93 g/d reflecting a daily protein consumption between 17 and 212 g/d or 0.29 g/kg bw/d and 2.6 g/kg bw/day, respectively. Between nitrogen excretion rate and endogenous creatinine clearance a non linear, highly significant correlation was found showing a saturation with a maximum endogenous creatinine clearance of 181.7 ml/min (dose response curve). A similar correlation was observed between urea excretion rate and endogenous creatinine clearance. Using a model for multiple regression analysis the dependence of the albumin excretion rate on nitrogen excretion rate and endogenous creatinine clearance was examined. Only a significant correlation was found between albumin excretion rate and endogenous creatinine clearance, while the correlation between albumin excretion rate and nitrogen excretion rate was not significant.
This investigation shows that chronic oral protein intake of widely varying amounts of protein is a crucial control variable for the glomerular filtration rate in subjects with healthy kidneys. It is suggested that these changes reflect in part structural changes of the glomerulus and tubules due to chronic protein intake.
关于长期口服蛋白质摄入对肾功能的影响，人们了解得相对较少。在大多数研究中，仅研究了蛋白质摄入量的短期变化（6 - 28天）或急性蛋白质负荷对肾小球滤过率的影响。本研究的目的是调查长期口服蛋白质摄入对内源性肌酐清除率和白蛋白排泄率的影响。
在一项前瞻性研究中，对88名肾功能正常的健康志愿者进行了检查（32名素食者、12名未补充蛋白质浓缩物的健身者、28名补充了蛋白质浓缩物的健身者以及16名无特殊饮食的受试者）。为了研究长期口服蛋白质摄入的影响，参与者遵循其饮食至少4个月。
作为肾小球滤过率指标的内源性肌酐清除率分别在32毫升/分钟至197毫升/分钟或34至186毫升/分钟×1.73平方米之间变化。氮排泄率被用作每日蛋白质摄入量的指标，因为已知它与每日蛋白质摄入量呈线性相关。氮排泄率在2.66克/天至33.93克/天之间，分别反映每日蛋白质摄入量在17至212克/天或0.29克/千克体重/天至2.6克/千克体重/天之间。在氮排泄率和内源性肌酐清除率之间发现了非线性的高度显著相关性，显示出内源性肌酐清除率最大值为181.7毫升/分钟时的饱和状态（剂量反应曲线）。在尿素排泄率和内源性肌酐清除率之间也观察到了类似的相关性。使用多元回归分析模型，研究了白蛋白排泄率对氮排泄率和内源性肌酐清除率的依赖性。仅在白蛋白排泄率和内源性肌酐清除率之间发现了显著相关性，而白蛋白排泄率与氮排泄率之间的相关性不显著。
本研究表明，长期口服不同量的蛋白质是健康肾脏受试者肾小球滤过率的关键控制变量。建议这些变化部分反映了由于长期蛋白质摄入导致的肾小球和肾小管的结构变化。
