Nephrology Division, Baylor University Medical Center, Dallas, Texas; Texas A&M School of Medicine, Bryan.
Department of Pathology, Baylor University Medical Center, Dallas Texas.
Am J Med. 2021 Sep;134(9):1170-1174. doi: 10.1016/j.amjmed.2021.03.017. Epub 2021 Apr 20.
Pseudohyperchloremia results in a very low or negative anion gap. Historically, the most common cause of this artifact was bromide poisoning. Bromide salts have been removed from most medications and bromism has become very uncommon. More recently, the introduction of chloride ion selective sensing electrodes (Cl-ISE) has generated a new cause of pseudohyperchloremia-salicylate poisoning. We describe 5 such patients and quantitate the error generated by this measurement artifact.
The magnitude of artifactual hyperchloremia generated by high salicylate levels was quantified in 5 patients by measuring chloride concentration with several Cl-ISEs from different manufacturers and with Cl-ISEs of different "ages," and comparing these results to measurements with a chloridometer (coulometric titration), which is free of the salicylate artifact.
Cl-ISEs from different manufacturers generated a wide range of artifactual chloride concentration elevation. Furthermore, the same Cl-ISE generated increasingly severe pseudohyperchloremia as it was repeatedly reused over time and "aged."
Salicylate interferes with measurement of the blood chloride concentration when a Cl-ISE is used. The severity of this artifact is related to the salicylate level, the specific Cl-ISE, and the "age" of the electrode. Toxic blood salicylate levels can generate marked pseudohyperchloremia, and consequently, an artifactual very small or negative anion gap. The large anion gap metabolic acidosis typical of salicylate poisoning is masked by this artifact. Salicylate has become the most common cause of pseudohyperchloremia, and physicians should immediately consider salicylate poisoning whenever the combination of hyperchloremia and a very small or negative anion gap is reported by the laboratory.
假性高氯血症导致非常低或负的阴离子间隙。历史上，这种伪影最常见的原因是溴化物中毒。溴化物盐已从大多数药物中去除，溴中毒已变得非常罕见。最近，氯离子选择性感应电极（Cl-ISE）的引入产生了一种新的假性高氯血症-水杨酸盐中毒的原因。我们描述了 5 例此类患者，并定量分析了这种测量伪影产生的误差。
通过使用来自不同制造商的几种 Cl-ISE 以及不同“年龄”的 Cl-ISE 测量 5 例患者中高水杨酸盐水平产生的人为高氯血症的幅度，并将这些结果与无水杨酸盐伪影的氯计（库仑滴定）的测量结果进行比较。
不同制造商的 Cl-ISE 产生了广泛的人为氯化物浓度升高。此外，随着时间的推移和“老化”，同一 Cl-ISE 重复使用时会产生越来越严重的假性高氯血症。
当使用 Cl-ISE 时，水杨酸盐会干扰血液氯浓度的测量。这种伪影的严重程度与水杨酸盐水平、特定的 Cl-ISE 和电极的“年龄”有关。有毒的血液水杨酸盐水平可产生明显的假性高氯血症，进而导致人为的非常小或负的阴离子间隙。这种伪影掩盖了典型的水杨酸盐中毒的大阴离子间隙代谢性酸中毒。水杨酸盐已成为假性高氯血症最常见的原因，每当实验室报告高氯血症和非常小或负的阴离子间隙的组合时，医生应立即考虑水杨酸盐中毒。
