The estimated glomerular filtration rate is a rather important measurement for patients under intensive care, since they often receive several drugs, and impaired renal function may result in misleading dosing. The estimated glomerular filtration is derived from mathematical models using serum creatinine, a measurement that suffers interference of some drugs, such as metamizole. The study intented to evaluate the impact on patient stratification for dose adjustment of two antimicrobials (meropenem and vancomycin) caused by metamizole interference in creatinine measurement by dry chemistry. A cross-sectional study was conducted with a group of 108 hospitalized patients under metamizole prescriptions at fixed intervals. Serum creatinine levels were determined by enzymatic dry chemistry and Jaffé assays and the estimated glomerular filtration rate was calculated through the CKD-EPI equation. Patients were stratified in groups according to their estimated glomerular filtration rate for drug dosing of vancomycin and meropenem. As expected, creatinine values were significantly lower in measurements performed by the dry chemistry method in comparison to Jaffé assay (p<0.0001) when patients are under metamizole treatment. A significant bias (-40.3%) was observed between those two methods, leading to a significant difference (p<0.0001) in patient classification according to renal function using the CKD-EPI equation for dosing adjustment. Thus, during the validity of metamizole treatment, the stratification for drug dosing by the estimated glomerular filtration rate is not reliable if the creatinine measurement is done through dry chemistry. Clinical and laboratory staff must be aware of these limitations and cooperate to optimize pharmacotherapy.

估计的肾小球滤过率对于重症监护患者来说是一个相当重要的衡量标准，因为他们经常接受多种药物，而肾功能受损可能会导致剂量错误。估计的肾小球滤过率来自使用血清肌酐的数学模型，血清肌酐测量值会受到某些药物（如安乃近）的干扰。该研究旨在评估安乃近干扰干化学法测定肌酐对两种抗菌药物（美罗培南和万古霉素）的剂量调整对患者分层的影响。对一组 108 名住院患者进行横断面研究，这些患者按固定时间间隔服用安乃近处方。血清肌酐水平由酶促干化学和 Jaffé 测定确定，估计的肾小球滤过率通过 CKD-EPI 方程计算。患者根据万古霉素和美罗培南药物给药的估计肾小球滤过率进行分组。正如预期的那样，当患者接受安乃近治疗时，与 Jaffé 测定 (p<0.0001) 相比，干化学法测量的肌酐值显着降低。在这两种方法之间观察到显着偏差 (-40.3%)，导致根据肾功能使用 CKD-EPI 方程进行剂量调整的患者分类存在显着差异 (p<0.0001)。因此，在安乃近治疗的有效期内，如果肌酐测量是通过干化学法进行的，那么根据估计的肾小球滤过率对药物剂量进行分层是不可靠的。临床和实验室工作人员必须意识到这些局限性并合作优化药物治疗。