Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
Department of Laboratory Medicine, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Korea.
Ann Lab Med. 2018 May;38(3):255-260. doi: 10.3343/alm.2018.38.3.255.
Measurement of thiopurine metabolites is helpful to monitor adverse effects and assess compliance in patients on thiopurine treatment. The purpose of this study was to develop and validate an analytical method for measurement of thiopurine metabolites, thioguanine nucleotides (6-TGN) and 6-methylmercaptopurine nucleotide (6-MMPN), in RBCs. We developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of 6-TGN and 6-MMPN and evaluated the stability of the thiopurine metabolites in RBC and whole blood states without any preprocessing at various storage conditions. The linear range was 0.1-10 μmol/L and 0.5-100 μmol/L for 6-TGN and 6-MMPN, respectively. The mean extraction recovery at the two concentrations was 71.0% and 75.0% for 6-TGN, and 102.2% and 96.4% for 6-MMPN. Thiopurine metabolites in preprocessed RBC samples were stable at 25°C and 4°C after storage for 4 hours and at -70°C for up to 6 months. However, 6-TGN decreased by 30% compared with the initial concentration when stored at -20°C for 180 days. In whole blood states, 6-TGN decreased by about 20% at four days after storage at 4°C. We validated a reliable LC-MS/MS method and recommend that the patient's whole blood sample be preprocessed as soon as possible.
测定硫嘌呤代谢物有助于监测硫嘌呤治疗患者的不良反应并评估其依从性。本研究旨在开发和验证一种用于测定红细胞中硫嘌呤代谢物硫鸟嘌呤核苷酸（6-TGN）和 6-甲基巯基嘌呤核苷酸（6-MMPN）的分析方法。我们开发并验证了一种用于定量测定 6-TGN 和 6-MMPN 的液相色谱-串联质谱（LC-MS/MS）方法，并评估了在无需任何预处理的情况下，在各种储存条件下，红细胞和全血状态下硫嘌呤代谢物的稳定性。6-TGN 和 6-MMPN 的线性范围分别为 0.1-10 μmol/L 和 0.5-100 μmol/L。两种浓度下 6-TGN 的平均提取回收率分别为 71.0%和 75.0%，6-MMPN 的平均提取回收率分别为 102.2%和 96.4%。预处理后的 RBC 样本中，硫嘌呤代谢物在 25°C 和 4°C 下储存 4 小时以及在-70°C 下储存长达 6 个月时稳定。然而，与初始浓度相比，-20°C 下储存 180 天时 6-TGN 减少了 30%。在全血状态下，4°C 储存 4 天后 6-TGN 减少了约 20%。我们验证了一种可靠的 LC-MS/MS 方法，并建议尽快对患者的全血样本进行预处理。
