First-trimester reference intervals for thyrotropin, free thyroxine, free thyroxine index and thyroxine for the Beckman Coulter UniCel(R) DxI 800 and Roche Modular Analytics E170 analyzers.

摘要

Thyroid disease is a common endocrine disease affecting women of reproductive age [1 ]. Thyroid disorders can occur during pregnancy and may be associated with a number of complications including increased risk of miscarriage, impaired neurological development, low birth weight, placental abruption, preedampsia and fetal death [2-4], Interpretation of thyroid function tests during pregnancy can be difficult because of complex hormonal changes which are most pronounced in the first-trimester [5]. For this reason both the American Association of Clinical Endocrinologists and the American Thyroid Association recommend measurements of both TSH and FT4 or FTI in pregnant patients with a history of thyroid dysfunction or those who present with symptoms [1 ]. In the first trimester, the fetus is reliant on transplacental passage of maternal thyroxine before the fetal thyroid gland becomes active between 16 and 20 weeks [6,7]. Due to the vulnerability of the fetus in the first trimester, it has been recommended that both method-specific and trimester-specific reference intervals (RIs) be established during pregnancy for TSH and FT4 [5,8]. The focus of our study is to establish RIs for TSH, FT4, FTI, and T4 for two different commercial analyzers using a large population of women in the first trimester of pregnancy. RIs from the first trimester were compared to healthy non-pregnant adults. Method comparison was performed using the results from the pregnant subjects for all thyroid function tests.