Department of Endocrinology, Austin Health, Melbourne, Australia.
Ann Clin Biochem. 2013 Nov;50(Pt 6):595-602. doi: 10.1177/0004563213486450. Epub 2013 Jul 19.
Trimester-specific reference intervals (RIs) for thyroid function tests are lacking for Beckman Dxl 800 analysers. We aimed to establish RIs for thyroid stimulating hormone (TSH), free thyroxine (fT4) and to track intraindividual changes in thyroid function throughout pregnancy.
One hundred and thirty healthy women without antithyroid peroxidase antibodies were followed longitudinally. Thyroid function was determined at trimester-1 (T1): 9-13 weeks; trimester-2 (T2): 22-26 weeks; trimester-3 (T3): 35-39 weeks and postpartum (PP): 8-12 weeks. A subgroup (n = 47) was used to track intraindividual changes using PP as non-pregnant state (baseline).
For trimesters 1-3, TSH (median (2.5th, 5th, 95th and 97.5th percentile)) was 0.77 (0.03, 0.05, 2.33, 3.05), 1.17 (0.42, 0.47, 2.71, 3.36) and 1.35 (0.34, 0.42, 2.65, 2.83) mIU/L, respectively. Free T4 (mean (95%CI)) was 10.7 (5.9-15.5), 8.1 (4.9-11.3), 7.8 (4.5-11.0) pmol/L, respectively. In T2 and T3, 36% and 41% of the fT4 values, respectively, fell below the non-pregnancy lower normal limit. In the subgroup assessed for longitudinal changes, of the women with baseline TSH ≤ median, 71-75% remained at or below the corresponding median for trimesters 1-3. Of the women with baseline fT4 ≤ median, 69-81% also remained at or below the corresponding median for trimesters 1-3. High correlation was observed at different trimesters and baseline for TSH (Spearman's r: 0.593-0.846, P < 0.001) and for fT4 (r: 0.480-0.739, P < 0.001).
Use of trimester-specific RIs would prevent misclassification of thyroid function during pregnancy. In the majority of women, TSH and fT4 tracked on the same side of the median distribution, from a non-pregnant baseline, throughout pregnancy.
贝克曼 Dxl 800 分析仪缺乏用于甲状腺功能检测的特定孕期参考区间 (RI)。我们旨在建立促甲状腺激素 (TSH)、游离甲状腺素 (fT4) 的 RI，并跟踪整个孕期个体内甲状腺功能的变化。
130 名无抗甲状腺过氧化物酶抗体的健康女性进行了纵向随访。在孕 1 期 (T1)：9-13 周；孕 2 期 (T2)：22-26 周；孕 3 期 (T3)：35-39 周和产后 (PP)：8-12 周测定甲状腺功能。一个亚组 (n=47) 用于使用 PP 作为非妊娠状态 (基线) 跟踪个体内的变化。
对于 1-3 个孕期，TSH（中位数 (2.5%、5%、95%和 97.5%分位数)）分别为 0.77（0.03、0.05、2.33、3.05）、1.17（0.42、0.47、2.71、3.36）和 1.35（0.34、0.42、2.65、2.83）mIU/L。游离 T4（均值 (95%CI)）分别为 10.7（5.9-15.5）、8.1（4.9-11.3）、7.8（4.5-11.0）pmol/L。在 T2 和 T3 中，分别有 36%和 41%的 fT4 值低于非妊娠低值下限。在评估纵向变化的亚组中，基线 TSH≤中位数的女性中，71-75%在 1-3 个孕期仍处于或低于相应的中位数。在基线 fT4≤中位数的女性中，69-81%在 1-3 个孕期仍处于或低于相应的中位数。在不同孕期和基线时，TSH（Spearman's r：0.593-0.846，P<0.001）和 fT4（r：0.480-0.739，P<0.001）的相关性均较高。
使用特定孕期的 RI 可以防止在怀孕期间错误分类甲状腺功能。在大多数女性中，从非妊娠基线开始，TSH 和 fT4 在整个孕期都沿着中位数分布的同一侧跟踪。
