Rocky Mountain Poison and Drug Center , Denver, CO , USA.
Clin Toxicol (Phila). 2014 Jul;52(6):611-7. doi: 10.3109/15563650.2014.918628. Epub 2014 May 20.
Nitromethane interferes with Jaffé measurements of creatinine, potentially mimicking acute kidney injury.
We determined the proportional contribution of nitromethane in blood samples to creatinine measured by the Jaffé colorimetric and the point-of-care (POC) reactions and determined whether the difference can reliably estimate the concentration of nitromethane. Additionally, we determined whether the presence of nitromethane interferes with anion/osmolal gaps and ascertained the stability of nitromethane in serum after 7 days.
Nitromethane was added to whole blood from four healthy volunteers to achieve concentrations of 0, 0.25, 0.5, 1, and 2 mmol/L. The following tests were performed: creatinine (Jaffé and POC), electrolytes (associated with Jaffé and POC), osmolality and nitromethane concentration (gas chromatography [GC]). Remaining samples were refrigerated and reanalyzed using GC at 7 days. Anion and osmolal gaps were calculated. Proportional recovery and degradation of nitromethane were measured using GC. Data were analyzed for agreement with single-factor ANOVA (p = 0.05).
Mean creatinine for POC and Jaff methods were 0.93 vs. 0.76 mg/dL, respectively. Jaff creatinine concentrations increased linearly with increasing nitromethane concentrations (R(2) = 1, p = 0.01): measured creatinine (mg/dL) = 7.1*nitromethane (mmol/L) = 0.79. POC creatinine remained unchanged across the range of nitromethane concentrations (p = 0.99). Anion and osmolal gaps also remained unchanged. Nitromethane was reliably identified in all sample concentrations using GC on Day 0. Detection of 0.25 mmol/L nitromethane was not consistently recovered on Day 7. Nitromethane degradation was most pronounced at 2 mmol/L concentrations (81% recovery).
Nitromethane alters apparent concentration of creatinine using the Jaffé reaction in a linear fashion but not when using the POC reaction. Measured difference between Jaffé and POC creatinine may identify the presence and estimate concentration of nitromethane. Presence of nitromethane did not alter the anion or osmolal gap; thus it would not potentially interfere with the diagnosis of co-exposure to a toxic alcohol.
硝基甲烷会干扰肌氨酸酐的 Jaffé 测量，从而潜在地模拟急性肾损伤。
我们确定了血液样本中硝基甲烷对 Jaffé 比色法和即时检测（POC）反应测量的肌氨酸酐的比例贡献，并确定这种差异是否能可靠地估计硝基甲烷的浓度。此外，我们还确定了硝基甲烷的存在是否会干扰阴离子/渗透压间隙，并确定了血清中硝基甲烷在 7 天后的稳定性。
将硝基甲烷加入来自四名健康志愿者的全血中，以达到 0、0.25、0.5、1 和 2 mmol/L 的浓度。进行了以下测试：肌氨酸酐（Jaffé 和 POC）、电解质（与 Jaffé 和 POC 相关）、渗透压和硝基甲烷浓度（气相色谱 [GC]）。其余样本冷藏，并在 7 天使用 GC 重新分析。计算阴离子和渗透压间隙。使用 GC 测量硝基甲烷的比例回收和降解。使用单因素方差分析（p = 0.05）分析数据的一致性。
POC 和 Jaff 方法的平均肌氨酸酐分别为 0.93 和 0.76 mg/dL。Jaff 肌氨酸酐浓度随硝基甲烷浓度的增加呈线性增加（R²=1，p=0.01）：测量肌氨酸酐（mg/dL）= 7.1*硝基甲烷（mmol/L）= 0.79。在硝基甲烷浓度范围内，POC 肌氨酸酐保持不变（p=0.99）。阴离子和渗透压间隙也保持不变。在第 0 天使用 GC 可以可靠地在所有样本浓度中识别出硝基甲烷。在第 7 天，0.25 mmol/L 硝基甲烷的检测未得到一致恢复。在 2 mmol/L 浓度下，硝基甲烷的降解最为明显（81%回收）。
硝基甲烷以线性方式改变 Jaffé 反应中肌氨酸酐的表观浓度，但当使用 POC 反应时则不会。Jaffé 和 POC 肌氨酸酐之间的测量差异可能识别出硝基甲烷的存在并估计其浓度。硝基甲烷的存在不会改变阴离子或渗透压间隙；因此，它不会潜在地干扰对同时接触有毒醇的诊断。
