Acute kidney injury (AKI) is a frequent, serious complication in critically ill patients. Even if renal replacement therapy is rapidly initiated, AKI may lead to the acute accumulation of metabolic waste products called uremic toxins (UTs). Although the accumulation and effects of UTs have been extensively described in the setting of chronic kidney disease (CKD), few data are available for AKI. A rapid, sensitive, specific method with simple sample preparation is required to facilitate routine blood monitoring of UTs in a context of acute accumulation.

We have developed and validated two fast liquid chromatography tandem mass spectrometry methods for the quantification of seven UTs in human serum. The first method (in negative ionization mode) enables the quantification of five UTs (hippuric acid (HA), indoxyl sulfate (IxS), para-cresyl sulfate (pCS), para-cresyl glucuronide (pCG), 3-carboxy-4-methyl-5-propyl-2-furanpropionate (CMPF)). The second method (in positive ionization mode) enables the quantification of two UTs (indole-3-acetic acid (IAA), and trimethylamine N-oxide (TMAO)). Sample preparation consisted of the deproteinization of a small volume of serum (50 µL). The run-times required to assay all the UTs in negative and positive ionization modes were only 2.5 and 2 min, respectively. In order to obtain a reliable, toxin-free matrix for the preparation of calibration standards and quality controls, serum was pretreated with activated charcoal. We used these methods to determine the time course of UT accumulation in eight patients who developed an AKI after cardiac surgery.

The calibration curves ranged from 0.1 to 100 µg mL⁻¹ for all the UTs (except for IAA: 0.5 to 100 µg mL⁻¹), and the correlation coefficients were above 0.999 for all. The methods were reproducible, repeatable, and accurate, with all coefficients of variation and biases below 15%. The highest concentrations measured in patients with AKI were lower than those reported in CKD stages 4 and 5 but higher than those observed in patients with no impairment of renal function (particularly for IxS and pCS). Our results also highlighted low accumulation of the other toxins (IAA, HA, TMAO, pCG, and CMPF). The UT concentrations did not rise earlier than that of creatinine; although the return to baseline took longer than for creatinine for some compounds. Lastly, assessment of the time course of UT accumulation as a prognostic marker for AKI (particularly for pCS and IxS) appears to be promising and should be continued in a larger number of patients.

急性肾损伤（AKI）在重症患者中是常见的严重并发症。即使迅速开始肾脏替代治疗，AKI也可能导致称为尿毒症毒素（UTs）的代谢废物的急性积累。尽管在慢性肾脏病（CKD）的背景下已广泛描述了UT的积累和作用，但AKI的数据很少。需要一种快速，灵敏，特异的方法和简单的样品制备方法，以利于在急性积累的情况下对UTs进行常规血液监测。

我们已经开发并验证了两种快速液相色谱串联质谱法，用于定量测定人血清中的7种UT。第一种方法（在负电离模式下）能够定量五个UT（马尿酸（HA），硫酸吲哚酚（IxS），对-甲苯基硫酸酯（pCS），对-甲苯磺酰基葡糖醛酸苷（pCG），3-羧基-4-甲基-5-丙基-2-呋喃丙酸酯（CMPF））。第二种方法（在正电离模式下）能够定量两个UT（吲哚-3-乙酸（IAA）和三甲胺N-氧化物（TMAO））。样品制备包括少量血清（50 µL）的脱蛋白。以负电离和正电离模式分析所有UT所需的运行时间分别仅为2.5分钟和2分钟。为了获得可靠的无毒素基质以用于制备校准标准品和质量控制，对血清进行了活性炭预处理。我们使用这些方法来确定八名在心脏手术后发生AKI的患者中UT累积的时间过程。

对于所有UT ，校准曲线的范围为0.1至100 µg mL ^-1（IAA除外：0.5至100 µg mL ^-1），且所有相关系数均高于0.999。该方法具有可重复性，可重复性和准确性，所有变异系数和偏差均低于15％。AKI患者中测得的最高浓度低于CKD第4和5期中报告的浓度，但高于无肾功能损害的患者（尤其是IxS和pCS）观察到的最高浓度。我们的结果还强调了其他毒素（IAA，HA，TMAO，pCG和CMPF）的低积累。UT的浓度没有比肌酐升高的时间早。尽管对于某些化合物，返回基线所需的时间比肌酐所需的时间更长。最后，评估UT积累作为AKI（尤其是pCS和IxS）的预后指标的时间过程似乎很有希望，应在更多患者中继续进行。