Endocrine Abstracts

Introduction: Subclinical hypothyroidism (subhypo) is linked to gestational hypertension (gestHT) and preeclampsia. Thyroid hormones have major influence on mitochondrial activity and the mitochondrial membrane potential (MMP) reflects the functional status of the mitochondria.

Aim: The aim was to estimate whether mitochondrial function is impaired in pregnant women with or without gestHT.

Methods: We included third trimester pregnant women consulting the department of obstetrics. The cases had subhypo (raised concentrations of TSH and normal concentrations of thyroid hormones). The second group were healthy pregnant women. The third group represented healthy non-pregnant women as controls. None of the women had any thyroid disease or medication. A blood sample was drawn to measure TSH and thyroid hormone. The mitochondrial function of stained mononuclear blood cells were measured by flow cytometry. GestHT was defined as blood pressure ≥140/90 mmHg.

Results: We present preliminary results of 102 patients and 40 controls. The prevalence of subhypo among pregnant women was 17%. The MMP was increased among pregnant women vs controls (P=0.03) and MMP was further increased among pregnant women having gestHT (P=0.01), an increase which was absent in pregnant women with gestHT and subhypo. Reactive oxygen species (ROS) was increased in pregnant women vs controls (P=0.006) but we found no differences in ROS between healthy pregnant women and women having gestHT. We have not yet examined the subgroup with subhypo.

Conclusion: The 17% prevalence of subhypo in pregnant women is higher than the commonly cited prevalence of 2–3%. The MMP of pregnant women was increased compared to non-pregnant women and further increased when gestHT was present. We suggest a possible physiological adaptation, which was absent in subhypo. This observation of an impaired mitochondrial function in subhypo may elucidate the higher frequency of complications like gestHT and preeclampsia in pregnant women with subhypo.