SAT494 Impending Thyroid Storm during Pregnancy in a Patient with Gestational Trophoblastic Disease

Disclosure: R. Kulkarni: None. Z. Sibai: None. Background: Gestational trophoblastic disease (GTD) is a rare complication of pregnancy that arises due to abnormal proliferation of trophoblasts of the placenta. The incidence of GTD in the United States of America is about 110 to 120 per 100,000 pregnancies. Abnormal trophoblastic proliferation leads to higher than expected B-HCG levels compared to normal pregnancy. Since the beta subunit of β-hCG has similar structure to TSH, β-hCG stimulates TSH receptor and causes hyperthyroidism during pregnancy which can be asymptomatic, mild or it can lead to severe cases of thyroid storm. Clinical Case: A 19-year-old African American woman with no PMH, 8 weeks primigravida presented with complaints of nausea, abdominal pain and difficulty walking. Associated symptoms included blurry vision, excessive sweating, tremors and palpitations. Physical examination finding included sinus tachycardia and low BMIof 18.6kg/m2, bilateral hand tremors, weakness of bilateral lower extremities. Initial labs showed quantitative β-hCG level of 283,163(H) m(iU)/mL, TSH <0.010 (L) m(iU)/L , FT4 2.54 (H) ng/dL, negativeTSI and TPO Abs. Burch-Wartofsky Point Scale score was 35 suggestive of impending thyroid storm. Pelvic ultrasound showed intrauterine pregnancy with estimated gestation age of 7 weeks 3 days with findings suggestive of fetal demise. Patient underwent Dilatation and Curettage for suspected molarpregnancy. Final histopathological report of aborted specimen verified the diagnosis of partial molar pregnancy. Based on clinical history, physical finding and lab results, patient was diagnosed with gestational trophoblastic disease induced impending thyroid storm. Endocrinology initiated management with Propranolol 40 mg TID and Methimazole 10 mg daily withimprovement in her clinical symptoms in two days. One week follow up as an outpatient showed resolution of symptoms, normalization of free T4 and down trending β-hCG titers to 166 m(iU)/mL. Propranolol and methimazole were stopped. Conclusion:Gestational trophoblastic disease although a rare clinical entity, it is potentially a life-threatening condition. β-hCG is a glycoprotein, and its beta subunit is structurally similar to TSH, allowing it to bind to the TSH receptor and causing hyperstimulation of the thyroid follicular cells leading to various degrees of hyperthyroidism. GTD associated with significant high level of β-HCG, in rare cases can cause severe consequences like thyroid storm. Therefore, GTD should be considered as a differential diagnosis in patient’s presenting with sever thyrotoxicosis during pregnancy. The mainstay of management is evacuation of the molar pregnancy. In severe cases of hyperthyroidism, Beta blocker and thioamides can be considered for symptoms relief and to speed the recovery. Follow-up with serial quantitative β-hCG measurements is crucial to evaluate for persistent molar tissue. Presentation Date: Saturday, June 17, 2023