Although liquid chromatography–tandem mass spectrometry (LC–MS/MS) assays for thyroglobulin (Tg) are resistant to autoantibody (TgAb) interference, recent studies have demonstrated approximately 40% of TgAb-positive individuals with recurrent thyroid cancer have Tg concentrations below the lower limit of quantification (LLOQ) of the LC–MS/MS assays described to date (i.e., <0.5 ng/mL), resulting in false-negative findings during post-thyroidectomy monitoring. To reduce false negative results due to insufficient analytical sensitivity, a new Tg assay was developed on a commercially available LC–MS/MS system operating at microliter/minute flow-rates (i.e., µLC–MS/MS) to maximize the analytical sensitivity and achieve a LLOQ of 0.02 ng/mL. When applied to the measurement of TgAb-negative and TgAb-positive patient serum samples previously measuring below the LLOQ of current immunometric and LC–MS/MS assays (LLOQ, 0.1–0.2 ng/mL), concentrations were measurable by µLC–MS/MS in 66% and 44% of samples, respectively – possibly explaining the persistence of TgAb in those patients. Patients with low Tg concentrations measured by µLC–MS/MS (<0.1 ng/mL) also exhibited elevation in their Tg concentrations upon hormone stimulation, indicating the detected Tg was produced from remnant thyroid tissue and would be suitable as a tissue biomarker. Forty-eight TgAb-positive patient specimens with undetectable Tg by both conventional LC–MS/MS (<0.15 ng/mL) and immunometric (<0.1 ng/mL) assays demonstrated measureable Tg concentrations by the new µLC–MS/MS assay in approximately one-third of the specimens, despite all patients being disease free at the time of collection, suggesting interference-free monitoring of low Tg levels may be feasible prior to the on-set of recurrent disease using a sensitive LC–MS/MS assay.

尽管甲状腺球蛋白 (Tg) 的液相色谱-串联质谱 (LC-MS/MS) 测定对自身抗体 (TgAb) 干扰具有抗性，但最近的研究表明，大约 40% 的 TgAb 阳性复发性甲状腺癌患者的 Tg 浓度低于迄今为止描述的 LC-MS/MS 分析的定量下限 (LLOQ)（即 <0.5 ng/mL），导致在甲状腺切除术后监测期间出现假阴性结果。为了减少由于分析灵敏度不足而导致的假阴性结果，在市售的 LC-MS/MS 系统上开发了一种新的 Tg 检测方法，该系统以微升/分钟流速（即 µLC-MS/MS）运行，以最大限度地提高分析灵敏度和达到 0.02 ng/mL 的 LLOQ。当应用于 TgAb 阴性和 TgAb 阳性患者血清样本的测量时，以前测量的结果低于当前免疫测定和 LC-MS/MS 测定的 LLOQ（LLOQ，0.1-0.2 ng/mL），浓度可通过 µLC-MS/分别在 66% 和 44% 的样本中出现 MS——可能解释了 TgAb 在这些患者中的持续存在。通过 µLC-MS/MS 测量的低 Tg 浓度 (<0.1 ng/mL) 的患者在激素刺激下也表现出 Tg 浓度升高，表明检测到的 Tg 是由残余甲状腺组织产生的，适合作为组织生物标志物。传统 LC-MS/MS (<0.15 ng/mL) 和免疫测定 (<0.