Department of Medicine, Division of Nephrology, University of Illinois at Chicago, Chicago, IL, USA.
Department of Medicine, Division of Nephrology, Johns Hopkins School of Medicine, Baltimore, MD, USA.
Nephrol Dial Transplant. 2020 May 1;35(5):846-853. doi: 10.1093/ndt/gfz042.
Residual kidney function (RKF) is thought to exert beneficial effects through clearance of uremic toxins. However, the level of native kidney function where clearance becomes negligible is not known.
We aimed to assess whether levels of nonurea solutes differed among patients with 'clinically negligible' RKF compared with those with no RKF. The hemodialysis study excluded patients with urinary urea clearance >1.5 mL/min, below which RKF was considered to be 'clinically negligible'. We measured eight nonurea solutes from 1280 patients participating in this study and calculated the relative difference in solute levels among patients with and without RKF based on measured urinary urea clearance.
The mean age of the participants was 57 years and 57% were female. At baseline, 34% of the included participants had clinically negligible RKF (mean 0.7 ± 0.4 mL/min) and 66% had no RKF. Seven of the eight nonurea solute levels measured were significantly lower in patients with RKF than in those without RKF, ranging from -24% [95% confidence interval (CI) -31 to -16] for hippurate, -7% (-14 to -1) for trimethylamine-N-oxide and -4% (-6 to -1) for asymmetric dimethylarginine. The effect of RKF on plasma levels was comparable or more pronounced than that achieved with a 31% higher dialysis dose (spKt/Vurea 1.7 versus 1.3). Preserved RKF at 1-year follow-up was associated with a lower risk of cardiac death and first cardiovascular event.
Even at very low levels, RKF is not 'negligible', as it continues to provide nonurea solute clearance. Management of patients with RKF should consider these differences.
残余肾功能（RKF）被认为通过清除尿毒症毒素发挥有益作用。然而，清除作用变得可以忽略不计的内源性肾功能水平尚不清楚。
我们旨在评估与无 RKF 的患者相比，“临床可忽略”的 RKF 患者之间非尿素溶质的水平是否存在差异。该血液透析研究排除了尿尿素清除率>1.5 mL/min 的患者，因为在此之下，RKF 被认为是“临床可忽略的”。我们从参与该研究的 1280 名患者中测量了 8 种非尿素溶质，并根据测量的尿尿素清除率计算了有和无 RKF 的患者之间溶质水平的相对差异。
参与者的平均年龄为 57 岁，57%为女性。在基线时，34%的纳入患者有临床可忽略的 RKF（平均 0.7±0.4 mL/min），66%的患者无 RKF。测量的 8 种非尿素溶质中有 7 种在有 RKF 的患者中明显低于无 RKF 的患者，范围从 hippurate 的-24%（95%置信区间[CI]：-31 至-16）到 trimethylamine-N-oxide 的-7%（-14 至-1）和 asymmetric dimethylarginine 的-4%（-6 至-1）。RKF 对血浆水平的影响与透析剂量增加 31%（spKt/Vurea 1.7 与 1.3）的效果相当或更明显。在 1 年随访时保留的 RKF 与较低的心脏死亡和首次心血管事件风险相关。
即使在非常低的水平，RKF 也不是“可以忽略的”，因为它继续提供非尿素溶质的清除。对有 RKF 的患者的管理应考虑到这些差异。
