Endocrine Abstracts

Background: During pregnancy, the immune system is suppressed. Therefore, autoimmune thyroid disorders (AITD) rarely appear in that period for the first time.

Case report: We present a case of a 30-year-old female firstly referred to our department in the 25th week of pregnancy because of 14-day-lasting arterial hypertension. At the systolic blood pressure between 140 and 160 mmHg, her dyastolic blood pressure was between 60 and 70 mmHg. She had been normotensive before hand and during previous pregnancy. She had no other symptoms or signs of hyperthyroidism. Laboratory tests revealed hyperthyroidism: TSH 0.005 mU/l (normal range 0.35–5.5 mU/l), free T₄ 28.6 pmol/l (normal range 11.5–22.7 pmol/l), and free T₃ 11.5 pmol/l (normal range 3.5–6.5 pmol/l). Thyroid gland was ultrasonographically enlarged, hypoechoic and lively perfused. Thyroid peroxidase antibodies were above 1300 KU/l (normal value below 60 KU/l), and TSH receptor antibodies 1 U/l (normal value below 1.5 U/l) Treatment with 3×50 mg of propilthiouracil daily was started. For arterial hypertension, methyldopa was introduced. One month later, free thyroid hormones and blood pressure normalized. In the 40th gestational week, she delivered a healthy baby daughter. Three weeks after delivery, she was normotensive without antihypertensive drugs. propilthiouracil was discontinued. In the next 4 months, she developed hypothyroidism and a substitution with L-thyroxine was started. The course of the disease revealed Hashimoto’s thyroiditis (HT) as a cause of hyperthyroidism in pregnancy, followed by a hypothyroidism after delivery.

Conclusion: Two important messages can be drawn from our case report. First, a divergent arterial hypertension in pregnancy can be the only and the warning sign of hyperthyroidism in that period. Secondly, in the second half of pregnancy, a hyperthyroid phase of HT can occur in spite of well-known amelioration of AITD in that period.