Department of Clinical Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Department of Laboratory Medicine, Ng Teng Fong General Hospital, Singapore.
Clin Chim Acta. 2020 Jan;500:172-179. doi: 10.1016/j.cca.2019.10.012. Epub 2019 Oct 26.
Anion gap (AG) aids the differential diagnosis of acid-base disorders. Its value has decreased, because of new analytical methods. Our goal was to compare AG reference intervals for different instruments and Southeast Asian populations.
We studied AG at three hospitals. One used the cobas 8000; two others, the Architect c16000. We included consecutive adults ≥18 years whose samples were sent for electrolytes and creatinine. We assessed AG for all patients and patients with normal electrolytes.
AG means differed significantly (P < 0.001) between the three hospitals for all patients and the normal electrolyte subgroup. AG reference intervals from all patients were 9-19, 5-15, and 5-15 mmol/L, and for the normal electrolyte subgroup, 10-17, 6-14, and 5-12 mmol/L, respectively. Compared to the normal albumin group, hypoalbuminemia patients showed lower AG in two hospitals (P < 0.001, P = 0.03), whereas patients with hyperalbuminemia demonstrated higher AG in all three hospitals (P < 0.001).
Different instruments produce different AGs. There is a weak correlation between albumin levels and AG. Laboratorians should verify reference intervals used when detecting laboratory errors and assisting clinicians in the differential diagnosis of acid base disorders and other medical conditions.
阴离子间隙（AG）有助于酸碱性紊乱的鉴别诊断。由于新的分析方法，AG 的价值已经降低。我们的目标是比较不同仪器和东南亚人群的 AG 参考区间。
我们在三家医院研究 AG。一家使用 cobas 8000；另外两家使用 Architect c16000。我们纳入了所有年龄≥18 岁的连续成人，其样本被送到电解质和肌酐处。我们评估了所有患者和电解质正常患者的 AG。
所有患者和正常电解质亚组的 AG 均值在三家医院之间差异显著（P<0.001）。所有患者的 AG 参考区间为 9-19、5-15 和 5-15mmol/L，正常电解质亚组的 AG 参考区间分别为 10-17、6-14 和 5-12mmol/L。与正常白蛋白组相比，在两家医院中低白蛋白血症患者的 AG 较低（P<0.001，P=0.03），而在所有三家医院中高白蛋白血症患者的 AG 较高（P<0.001）。
不同的仪器会产生不同的 AG。白蛋白水平与 AG 之间存在弱相关性。当检测实验室误差并协助临床医生鉴别酸碱性紊乱和其他医疗状况时，实验室人员应验证所使用的参考区间。
