Department of Laboratory Medicine, Yale School of Medicine, New Haven, CT.
J Appl Lab Med. 2020 Jan 1;5(1):126-135. doi: 10.1373/jalm.2019.029496.
The anion gap is primarily used in the diagnosis of acid-base disorders. We conducted a study to determine the anion gap reference interval in our patient population, investigated the workup of abnormal vs normal anion gaps, and examined the anion gap variation upon repeated testing.
A retrospective review was performed on 17137 adult and pediatric patients who presented to Yale-New Haven Hospital outpatient clinics, emergency department, or intensive care units between 2012 and 2017.
We derived a new reference interval of 7 to 18 mmol/L with a median of 13 mmol/L in healthy adults with no significant differences owing to partitioning by sex or age. Based on the new reference interval, 5%, 23%, and 18% of healthy, emergency department, and intensive care unit adult patients, respectively, were misclassified as having high values with the previous interval of 6 to 16 mmol/L. However, there were no significant differences in the number of tests ordered in patients with anion gaps above and below the upper limit of the previous reference interval. The majority of increased anion gaps that were repeated normalized by 12 h. In a subgroup of healthy adult patients with annual testing, the median percent change in each patient's anion gap from 2015 to 2016 was approximately 13%.
The anion gap should be used with an appropriate reference interval to avoid misclassification. There may be a moderate degree of individuality that argues for comparing the anion gap with its baseline value in the same patient pending further studies that formally derive its biological variation.
阴离子间隙主要用于酸堿平衡紊乱的诊断。我们进行了一项研究，以确定我们患者人群中的阴离子间隙参考区间，调查异常与正常阴离子间隙的检查情况，并检查重复测试时阴离子间隙的变化。
对 2012 年至 2017 年间在耶鲁纽黑文医院门诊、急诊或重症监护病房就诊的 17137 例成人和儿科患者进行回顾性分析。
我们得出了一个新的参考区间为 7 至 18 mmol/L，健康成年人的中位数为 13 mmol/L，性别或年龄无明显差异。根据新的参考区间，分别有 5%、23%和 18%的健康成年人、急诊患者和重症监护病房患者被错误地归类为高值，而之前的参考区间为 6 至 16 mmol/L。然而，在阴离子间隙高于和低于旧参考区间上限的患者中，所开检查的数量没有显著差异。大多数升高的阴离子间隙在 12 小时内恢复正常。在一组有年度检测的健康成年患者中，每位患者的阴离子间隙从 2015 年到 2016 年的中位数变化百分比约为 13%。
阴离子间隙应与适当的参考区间一起使用，以避免错误分类。可能存在一定程度的个体差异，这表明在进一步研究正式得出其生物学变异之前，应将阴离子间隙与其同一患者的基线值进行比较。
