Gestation‐specific changes in maternal thyroglobulin during pregnancy and lactation in an iodine‐sufficient region in China: a longitudinal study

Abstract

Our work demonstrates that Tg is elevated during pregnancy, and the effect of pregnancy should be taken into consideration when Tg is used as a biomarker for the iodine status. Cord blood Tg is much higher than maternal Tg levels at the 36w and is correlated with maternal iodine status.

The impact of isolated maternal hypothyroxinemia during the first and second trimester of gestation on pregnancy outcomes: an intervention and prospective cohort study in China

“…Our previous study conducted by Zhang et al [ 12 ] has confirmed that the FT4 concentrations measured by immunoassays in our study displayed a consistent tendency with liquid chromatography/tandem mass spectrometry (LC/MS) assays in the study by Kahric et al [ 13 ] and were negatively correlated with TSH ( r = − 0.201, p < 0.01) in the first trimester. Zhang et al [ 12 ] have indicated that the prevalence of hypothyroxinemia in the first and second trimester was 2.0% and 1.2–2.4%, respectively. The current studies showed that the incidence of the IMH was estimated at 2–4.3%, and may up to 25–30% [ 4 ].…”

“…Serum FT4 might be influenced by different assay methods. The classic equilibrium dialysis or ultrafiltration methods, as well as solid-phase extraction–liquid chromatography/tandem mass spectrometry methods have higher reliability and reproducibility [ 4 , 12 ]. However, these assays are laborious, time-consuming, expensive, and not widely available.…”

“…The intra-assay coefficients of variation (CV) of TSH, FT4, and TPOAb were 1.57–4.12%, 2.24–6.33%, and 2.42–5.63%, respectively. The inter-assay CVs were 1.26–5.76%, 4.53–8.23%, and 5.23–8.16%, respectively [ 12 ].…”

“…Therefore, we used trimester-specific diagnostic criteria to evaluate the thyroid function of the pregnant women in our study. For the first and second trimesters, the reference intervals for TSH (2.5th–97.5th percentile) were 0.35–4.13 mIU/L and 0.37–4.78 mIU/L, respectively, and the reference intervals for FT4 (2.5th–97.5th percentile) were 13.35–19.01 pmol/L and 10.45–16.22 pmol/L, respectively [ 12 ]. A control group was defined as TSH and FT4 within normal range (2.5th–97.5th percentile) and TPOAb < 34 IU/L.…”

Trimester-Specific Thyroid Function in Pregnant Women with Different Iodine Statuses

“…The study was conducted from March 2016 to May 2017. All participants were recruited while attending routine antenatal visits at Tanggu Maternity Hospital, Tianjin Child Health Care Service Center, and Gaoqing Child Health Hospital in different trimesters, including the first trimester (<13 gestational weeks [GW]), the second trimester (GW [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28], and the third trimester (≥28 GW). The exclusion criteria were as follows: (1) living in the local area for <5 years; (2) multiple pregnancy; (3) age below 18 or above 35 years; (4) personal/family history of thyroid disease; (5) history of autoimmune diseases; and (6) taking iodine supplements during pregnancy.…”