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为何连续腹膜透析中Kt/V和肌酐清除率可能不相关

Author
John M Burkart, MD
Section Editor
Thomas A Golper, MD
Deputy Editor
Alice M Sheridan, MD
Translators
毛志国, 副主任医师，副教授

引言

对于使用维持性血液透析或腹膜透析(peritoneal dialysis, PD)进行治疗的患者而言，透析充分性是一个重要问题。以前，基于观察性研究，大多数研究者认为，计算每周尿素清除指数(urea clearance index, Kt/Vurea, Kt/V)和腹膜肌酐清除率(creatinine clearance, CCr)都可以用于评估腹膜透析充分性。因此，2000年美国肾脏基金会(National Kidney Foundation, NKF)制定的《肾病预后质量指南(Kidney Disease Outcome Quality Initiative, K/DOQI)》提出充分透析需满足每周总Kt/V高于2.0和/或每周总CCr至少为60L/1.73m2体表面积(body surface area, BSA)[1-4]。

与此相比，基于前瞻性随机临床试验的结果，2006年NKF-K/DOQI指南推荐使用Kt/V作为透析剂量的“指标”，且未见同时使用Kt/V和CCr监测透析剂量有额外益处[5]。因此他们推荐只用Kt/V作为总溶质清除率目标值。 (参见“腹膜透析的充分性”)

然而，正文和临床实践推荐部分指出基于其他原因，获知每周CCr可能是有帮助的。虽然溶质清除率的这两个指标通常彼此相关，但两者数值矛盾并不罕见[6-8]。例如，在某些病例中，KT/V显示透析充分，CCr显示不够充分，且患者看似处于营养不良状态。其他一些患者体重增加且进食良好，但清除率参数都低于目标值。

如何解释这些现象？本专题将论述这个问题，首先从PD患者溶质清除率的基础开始总结。

腹膜透析的溶质清除率

如在任何形式的肾脏替代治疗中一样，总溶质清除率包括通过透析清除和残余肾清除去除有问题的溶质。与通常只用溶质的透析清除率衡量透析充分性的血液透析中心标准惯例相比，腹膜透析标准采用总溶质清除率(残余肾清除率和腹膜透析清除率)作为透析充分性的指标。后者反映了肾小球滤过与肾小管分泌和重吸收之间的平衡。肌酐和尿素都可自由滤过，但是，近端肾小管分泌进一步增加了肌酐清除率，而肾小管对尿素的重吸收减少了尿素清除率。因此，残肾肌酐清除率高估了肾小球滤过率，而尿素清除率低估了肾小球滤过率。因此，晚期肾衰竭患者的肾小球滤过率常常是通过计算上述两个清除率的平均值来估算的。  (参见“肌酐清除率的计算”)

   

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Literature review current through: 2017-06 . | This topic last updated: 2017-01-20.
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