Department of Nuclear Medicine, Hôpital Universitaire de Bruxelles (H.U.B) - Hôpital Erasme, Brussels, Belgium.
Instituto de Ciencias Naturales, Facultad de Medicina Veterinaria y Agronomía, Universidad de Las Américas, Santiago, Providencia, Chile.
Eur Thyroid J. 2024 Nov 25;13(6). doi: 10.1530/ETJ-24-0142. Print 2024 Dec 1.
Thyroglobulin (Tg) is a biomarker of iodine status. Newborn Tg is a more sensitive marker than neonatal TSH in detecting variations in iodine intake. This study aims to validate an enzyme-linked immunosorbent assay (ELISA) for Tg determination on dried blood spots (DBS) in newborns. This study also sets out to assess the stability of Tg and the influence of newborns' hematocrit on Tg determination.
A commercially available ELISA Tg assay was adapted for use on DBS. DBS-Tg in cord blood was measured in 209 newborns delivered from healthy euthyroid pregnant women. Sensitivity, linearity, repeatability, and intermediate fidelity were determined using the appropriate standards and quality control materials.
The limit of detection of the DBS-Tg assay was 2.4 µg/L, and the limit of quantification was 5.8 µg/L. Repeatability and intermediate fidelity were 7.7-8.3% and 11.0-11.2%, respectively. The median cord plasma Tg and DBS-Tg values in newborns were not significantly different, 30.2 (21.3-44.4) µg/L and 31.6 (19.3-48.7) µg/L (P = 0.48) with the ELISA, respectively, and 76.5 (40.0-101.5) µg/L with the Elecsys assay with an R = 0.88. DBS-Tg concentrations decrease with increasing hematocrit values (P < 0.05). DBS-Tg values were stable at a concentration of 25 µg/L for 12 months at -20ºC and 4ºC.
This DBS-Tg assay demonstrated good analytical performance over a wide range of Tg concentrations, suggesting it is well suited to detecting variations in Tg concentrations. Studies comparing populations with different prevalence of anemia should consider the effect of hematocrit on DBS-Tg determination. The availability of a DBS-Tg assay for newborns makes it possible to integrate iodine status monitoring with newborn screening for inherited metabolic diseases.
甲状腺球蛋白（Tg）是碘状态的生物标志物。与新生儿 TSH 相比，新生儿 Tg 是检测碘摄入量变化的更敏感标志物。本研究旨在验证一种用于检测新生儿干血斑（DBS）中 Tg 的酶联免疫吸附测定（ELISA）。本研究还旨在评估 Tg 的稳定性以及新生儿红细胞压积对 Tg 测定的影响。
对商业上可用的 ELISA Tg 测定法进行了修改，以用于 DBS。在 209 名来自健康甲状腺功能正常孕妇的新生儿中测量脐带血中的 DBS-Tg。使用适当的标准和质量控制材料确定灵敏度、线性度、重复性和中间精密度。
DBS-Tg 测定的检测限为 2.4 µg/L，定量限为 5.8 µg/L。重复性和中间精密度分别为 7.7-8.3%和 11.0-11.2%。新生儿脐带血浆 Tg 和 DBS-Tg 值中位数无显著差异，分别为 30.2（21.3-44.4）µg/L 和 31.6（19.3-48.7）µg/L（P=0.48），用 ELISA 法，分别为 76.5（40.0-101.5）µg/L，用 Elecsys 法 R=0.88。DBS-Tg 浓度随红细胞压积值的增加而降低（P<0.05）。DBS-Tg 值在浓度为 25 µg/L 时在-20°C 和 4°C 下可稳定保存 12 个月。
该 DBS-Tg 测定法在广泛的 Tg 浓度范围内表现出良好的分析性能，表明其非常适合检测 Tg 浓度的变化。比较具有不同贫血患病率的人群的研究应考虑红细胞压积对 DBS-Tg 测定的影响。新生儿 DBS-Tg 测定法的出现使得将碘状态监测与新生儿遗传性代谢疾病筛查相结合成为可能。
