Stinca Sara, Andersson Maria, Erhardt Jürgen, Zimmermann Michael B
Human Nutrition Laboratory, Institute of Food Nutrition and Health, Swiss Federal Institute of Technology (ETH) , Zurich, Switzerland .
Thyroid. 2015 Dec;25(12):1297-305. doi: 10.1089/thy.2015.0428. Epub 2015 Dec 1.
Thyroglobulin (Tg), a biomarker of iodine nutrition, can be measured on dried blood spots (DBS), which simplifies collection and transport in surveys. The World Health Organization recommends DBS-Tg for monitoring iodine status in children. It could also be a useful iodine biomarker during pregnancy. However, the Tg antibody (Ab) used in earlier DBS-Tg assays is no longer commercially available. The aims of the present study were: (i) to develop a new low-cost serum and DBS-Tg sandwich enzyme-linked immunosorbent assay for assessment of Tg in population studies; (ii) to check the stability of DBS-Tg during long-term storage; and (iii) to assess within-subject variability in DBS-Tg.
Serum and DBS samples were measured from healthy pregnant women (n = 424) with the new assays, as well as the Immulite 2000 (Siemens), including TgAb positive (n = 150) and TgAb negative (n = 274) women. DBS-Tg stability was tested over 15 weeks of storage at -20 °C. Within-subject variability was evaluated over four weeks in four healthy adults.
Intra-assay and interassay variability was 4.4-7.3% and 10.1-12.9% for the new serum Tg assay, and 7.6-12.3% and 7.6-16.5% for the DBS-Tg assay. Correlation between the two serum methods was high (r = 0.68, p < 0.01). Assay performance in all women and those TgAb negative was comparable. Correlation between the new serum Tg assay and the DBS-Tg assay was high (r = 0.78, p < 0.01), and agreement expressed as a function of the average Tg concentration for the two methods (X) was 0.59X -4.59 μg/L. DBS-Tg was stable for 15 weeks stored at -20 °C. Within-subject variability in DBS-Tg was 21.1%. Reagents and antibodies costs for the new serum and DBS assays are ∼ US$1.
These new low-cost serum and DBS-Tg assays perform well over a wide range of Tg concentrations, and the field-friendly DBS assay may be particularly useful in population studies of iodine nutrition.
甲状腺球蛋白（Tg）作为碘营养的生物标志物，可在干血斑（DBS）上进行检测，这简化了调查中的样本采集和运输过程。世界卫生组织推荐使用干血斑Tg检测来监测儿童的碘营养状况。它在孕期也可能是一种有用的碘生物标志物。然而，早期干血斑Tg检测中使用的Tg抗体已不再商业化供应。本研究的目的是：（i）开发一种新的低成本血清和干血斑Tg夹心酶联免疫吸附测定法，用于人群研究中Tg的评估；（ii）检查干血斑Tg在长期储存期间的稳定性；（iii）评估干血斑Tg的个体内变异性。
使用新检测方法以及西门子Immulite 2000对424名健康孕妇的血清和干血斑样本进行检测，其中包括Tg抗体（TgAb）阳性（n = 150）和TgAb阴性（n = 274）的女性。在-20°C下储存15周，测试干血斑Tg的稳定性。在四名健康成年人中评估四周内的个体内变异性。
新血清Tg检测的批内变异和批间变异分别为4.4 - 7.3%和10.1 - 12.9%，干血斑Tg检测的批内变异和批间变异分别为7.6 - 12.3%和7.6 - 16.5%。两种血清检测方法之间的相关性很高（r = 0.68，p < 0.01）。所有女性以及TgAb阴性女性的检测性能相当。新血清Tg检测与干血斑Tg检测之间的相关性很高（r = 0.78，p < 0.01），两种方法的Tg平均浓度（X）的一致性函数为0.59X - 4.59 μg/L。干血斑Tg在-20°C下储存15周稳定。干血斑Tg的个体内变异性为21.1%。新血清和干血斑检测的试剂和抗体成本约为1美元。
这些新的低成本血清和干血斑Tg检测方法在广泛的Tg浓度范围内表现良好，且对现场友好的干血斑检测在碘营养人群研究中可能特别有用。
