Hypothyroxinaemia during gestation is associated with low ferritin and increased levels of inflammatory markers

Abstract

Objective: Pregnancy is a state of physiological inflammation facilitating implantation. Early isolated hypothyroxinaemia (IH) and increased inflammation (including obesity) have been associated with severe obstetric complications. The current study evaluated the association between IH, low ferritin and inflammation parameters (interleukin 6 (IL-6), C-reactive protein (CRP), human chorionic gonadotrophin (hCG) and obesity. Moreover, the course of these parameters throughout pregnancy was evaluated in relation to IH. Methods: In the cross-sectional study (A) at 12 weeks, 2759 women participated and 2433 participated in the longitudinal study (B) with assessments at 12, 20 and 28 weeks gestation. At the first trimester, 122 (4.4%) IH women (free thyroxine (FT4) 95th percentile: OR: 1.9, 95% CI: 1.04–3.7), low hCG ( 30, OR: 1.7, 95% CI: 1.12.9) and higher age (OR: 1.1, 95% CI: 1.04–1.15). Longitudinally, compared to reference women, women with IH at 12 weeks gestation showed persistently and significantly lower ferritin and hCG levels, and persistently higher CRP and IL-6 levels throughout gestation. Conclusion: Gestational IH could be viewed as a condition of increased inflammation, as reported in non-thyroidal illness syndrome. Less favourable inflammation parameters and low iron status during early gestation in IH women seem to persist throughout gestation.

Keywords

• inflammation
• isolated hypothyroxinaemia
• pregnancy