Endocrine Abstracts

Introduction: Hyperthyroidism during pregnancy is uncommon, with an incidence of 0.1% to 0.4%, and is most commonly due to Graves’ disease. Human chorionic gonadotropin (hCG) can transiently stimulate the thyroid during early pregnancy. Differentiating between gestational transient thyrotoxicosis and Graves’ disease is crucial due to differing management strategies and associated maternal-fetal risks. We present a case of severe first-trimester thyrotoxicosis, likely triggered by hCG in the context of underlying Graves’ disease, successfully managed with short-term Lugol’s iodine in early gestation.

Case presentation: We report the clinical course of a 25-year-old pregnant woman presenting at 11 weeks of amenorrhea with intractable vomiting and severe thyrotoxicosis. Laboratory evaluation, thyroid ultrasound, and postpartum Tc99m scintigraphy were performed. Treatment included propylthiouracil (PTU) and Lugol’s iodine initiated during the first trimester, with regular biochemical monitoring throughout pregnancy.

Results: TSH was undetectable and FT4 was >90 pmol/l. TSI was mildly elevated (1.9 IU/l) and became negative by 15 weeks. FT4 decreased to 72 pmol/l within 48 hours of treatment. Lugol’s iodine was discontinued at Day 6, and PTU was continued, leading to normalization of thyroid hormones and liver enzymes. Delivery at 39 weeks was uneventful. Postpartum scintigraphy supported the diagnosis of Graves’ disease.

Conclusion: This case illustrates the importance of recognizing Graves’ disease in early pregnancy and demonstrates that short-term Lugol’s iodine may be a safe and effective adjunct in first-trimester management when rapid hormonal control is needed. Early diagnosis and timely intervention are key to reducing maternal and fetal complications. Close postpartum follow-up is essential to monitor for relapse.

Referencees: 1. De Groot L, Abalovich M, Alexander EK, et al. Management of thyroid dysfunction during pregnancy and postpartum: an Endocrine Society guideline. J Clin Endocrinol Metab 97, 2543–2565 (2012). 2. Bahn RS, Burch HB, Cooper DS, et al. Hyperthyroidism and other causes of thyrotoxicosis: management guidelines of the American Thyroid Association and American Association of Clinical Endocrinologists. Thyroid 21, 593–646 (2011). 3. Huang Y, Xu Y, Xu M, et al. Application of oral inorganic iodine in the treatment of Graves’ disease. Front Endocrinol (Lausanne) 14:1150036 (2023)

Keywords: Graves’ disease, pregnancy, thyrotoxicosis, Lugol’s iodine