Preeclampsia and Thyrotoxicosis: A Case of Impending Storm

Abstract

Abstract Introduction: Preeclampsia is a complication of pregnancy defined by new onset hypertension after 20 weeks with proteinuria or new onset thrombocytopenia, renal or liver dysfunction, pulmonary edema or cerebral/visual symptoms. Hyperthyroidism in pregnancy is usually due to Graves’ disease, and if poorly controlled can increase the risk of preeclampsia and thyroid storm. In this case report we present a case of preeclampsia with impending thyroid storm treated successfully with medical therapy, delivery, and plasmapheresis. Case Description: A 40-year-old female who is 31 6/7 weeks pregnant presents with cough and dyspnea. She has no known thyroid disease. Her systolic blood pressure at presentation is >160 mmHg. She is diagnosed with preeclampsia based on elevated spot protein/creatinine ratio (1.4 g/g) and persistent hypertension. A brain natriuretic peptide is elevated to 847 (reference range <= 100 pg/ml). Complete blood count and comprehensive metabolic panel are normal, with exception of mild alkaline phosphatase elevation. A CT pulmonary angiogram is negative for pulmonary embolism but shows bilateral pleural effusions. She is started on intravenous antihypertensive medications and furosemide. Due to persistent tachycardia, thyroid function is checked and is notable for a thyroid stimulating hormone level of 0.05 (non-pregnant reference range 0.35 – 4.94 mIU/L), an elevated free T3 of 13.7 (non-pregnancy reference range 1.7 – 3.7 pg/ml), and an elevated free T4 > 4 (non-pregnancy reference range 0.70-1.48 ng/dL). She is started on therapy for impending thyroid storm, including maximum doses of propranolol, propylthiouracil, hydrocortisone and saturated solution of potassium iodide. Her thyroid stimulating immunoglobulin is > 500 (reference range <= 122%) and TSH receptor antibody is > 40 (reference range <= 1.75 iU/L) leading to a new diagnosis of Graves’ disease. On hospital day three, she develops altered mental status and fetal bradycardia, warranting emergency cesarean section. On hospital day five she develops worsening confusion, abnormal liver function tests and increasing levels of free T4 and free T3. At this time, she is started on plasmapheresis therapy. Free T4 and free T3 values normalize after two rounds. Her medications are slowly weaned, and she is discharged from the hospital on methimazole 20 mg daily. Her baby is discharged after a brief hospital stay for sequela of prematurity. Discussion: While far less common than preeclampsia, thyrotoxicosis may present with similar symptomatology and can pose significant morbidity and mortality risk for pregnant patients. However, with prompt diagnosis and appropriate therapies, the disorder can be treated successfully and without lasting harm to the mother or fetus. For these reasons, it should remain on the differential for patients with symptoms of preeclampsia, and thyroid studies should be considered.