Endocrine Abstracts

Introduction: The aim of our study was to evaluate the causes of thyrotoxicosis detected during pregnancy as well as to determine the prevalence of thyroid nodular disease (TND) in our population and which factors are associated with this condition.

Methods: We performed a retrospective review of 1,760 patients between April 2014 and September 2017 remitted from the gynecology department due to thyroid dysfunction detected in the 9^th week of pregnancy (universal screening of TSH). Among these patients, 131 presented thyrotoxicosis, defined as TSH<0.13 (reference range of TSH in the first trimester of gestation in our center: 0.13–4.16 mU/l). Patients with known TND (n=9), hyperemesis gravidarum (n=5) and multiple pregnancy (n=17) were excluded. All the patients received iodine supplementation during pregnancy. Thyroid function was evaluated throughout pregnancy and thyroid ultrasound was performed if the TSH remained decreased after the 20^th week or if cervical palpation was abnormal. Comparisons within the group were done by T-student test or U-Mann Whitney using STATA program.

Results: Of the 100 patients studied, four were diagnosed with Graves’ disease (TRAb-positivity) and 96 with gestational thyrotoxicosis (GT). Among patients with GT, the mean age was 34.3(5.4) years and there were 30 nuliparous (31.2%), 49 uniparous (51.1%) and 17 multiparous (gravidity ≥2, 17.7%). The sample consisted predominantly of Caucasians (n=76, 79.2%). The level of TSH in the first trimester was undetectable in 55.2% of patients. There was positive thyroid autoimmunity (defined as the presence of TgAb or TPOAb) in 16 patients (16.7%). There were 9 patients (9.4%) who had received treatment with in vitro fertilization. In 50 women, thyrotoxicosis was transient (TRAB-negativity, normal TSH>20^th week and normal thyroid palpation). In the other cases (n=46), thyroid ultrasound was performed. Thyroid nodules (>2 mm) on ultrasonography were detected in 26 patients, (giving a TND prevalence of 56.5%), with 21 subjects having a nodule >10 mm. Fourteen women had clinically palpable nodules. Women with thyroid nodules were older (36.6±4.9 vs 32.8±5.0 yr, P:0.02) and had higher gravidity (P:0.04) compared with women having no thyroid nodules. The subject with TND also had higher positive rate of autoimmunity, (26.9% vs 5%, P:0.05). No difference in TSH and FT4 was detected throughout pregnancy.

Conclusions: The main cause of hyperthyroidism in pregnant women is gestational thyrotoxicosis. In our population, the prevalence of TND in these women is high, so ultrasound should be considered. TND is associated with older age, greater gravidity and positive autoimmunity.