TSH reference values in the first trimester of gestation and correlation between maternal TSH and obstetric and neonatal outcomes: a prospective Brazilian study.

Pedro Weslley Rosario,Maria Regina Calsolari,Marina Carvalho

doi:10.1590/2359-3997000000132

Pedro Weslley Rosario, Maria Regina Calsolari + Show 1 more

Open Access

https://doi.org/10.1590/2359-3997000000132

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Abstract

To define the normal range of TSH in the first trimester of gestation and to evaluate the correlation between maternal TSH and obstetric and neonatal outcomes. Prospective study. Women without known or clinically suspected thyroid disease and without risk factors for thyroid dysfunction, who became pregnant spontaneously and were initially evaluated up to week 12 of gestation, were included. Women with positive anti-thyroperoxidase antibodies, twin pregnancy, hyperemesis gravidarum, and trophoblastic disease were excluded. In the 660 pregnant women, the mean, median, and 2.5th and 97.5th percentiles of TSH were 0.9, 0.96, 0.04 and 2.68 mIU/L, respectively. TSH was undetectable in 2%, < 0.5 mIU/L in 17.4%, > 2 mIU/L in 9.7%, > 2.5 mIU/L in 4.7%, and > 3 mIU/L in 1%. None of the women received levothyroxine or antithyroid drugs during pregnancy. In addition, there was no difference in obstetric or neonatal outcomes when women with TSH ≤ 0.1, between 0.1 and 2.5, and between 2.5 and 4 mIU/L were compared. In the population studied, the TSH value corresponding to the 97.5th percentile was 2.68 mIU/L in the first trimester of gestation.

Highlights

T SH is the most important test for the evaluation of thyroid function during pregnancy
Supporting its importance, levothyroxine (L-T4) replacement therapy should be considered in pregnant women with elevated TSH, even in the presence of normal T4 concentrations and in the absence of anti-thyroperoxidase antibodies (TPOAb) [1,2,3,4], while L-T4 treatment is controversial in pregnant women with normal TSH, even in the presence of hypothyroxinemia or circulating TPOAb [1,2,3,4]
We first highlight some characteristics of the study. This is the largest Brazilian study evaluating TSH concentrations in healthy pregnant women, in which the number of participants was much higher than that recommended by the NACB [7], selection was performed rigorously, including potentially interfering obstetric conditions [5], and the samples were adequately obtained

Summary

Introduction

T SH is the most important test for the evaluation of thyroid function during pregnancy. TSH; pregnant women; first trimester; reference values; obstetric and neonatal outcomes

Results

Conclusion