Abstract #1404976: Severe Gestational Thyrotoxicosis Complicated by Thyroid Storm in a Primigravid Patient with Hyperemesis Gravidarum in a Multiple Pregnancy

Abstract

Gestational transient thyrotoxicosis (GTT) is seen in 3% of pregnancies and occurs in 30-60% of patients with hyperemesis gravidarum (HG). The incidence of thyroid storm in this setting has not yet been reported. The severity of GTT and HG is positively related to serum hCG levels. Treatment in GTT with antithyroid drugs is not routinely indicated since GTT usually is described as a disorder of spontaneous resolution without unfavorable maternal and fetal outcomes. We describe a case of severe GTT complicated by thyroid storm in a primigravid 20-year-old patient with twin gestation and HG. A 20-year-old female primigravida with twin gestation and HG presented with nausea, vomiting, altered sensorium, and weakness for four days at 14 weeks’ gestation. At 9 weeks’ gestation during inpatient management for HG, TSH < 0.01 was found. Outpatient FT4 3.1 was obtained. On current presentation, tachycardia HR 169 bpm, mild abdominal tenderness, disorientation, a repeated TSH < 0.01 resulting in Burch-Wartofsky point scale of 45 warranted MICU admission for thyroid storm management. FT4 3.3, T3 239, and hCG level 99,080 were found. Transvaginal US and positive MSSA blood cultures confirmed spontaneous septic abortion. Antibiotics were given, and dilation and evacuation were performed. FT4 and T3 improved to 2.1 and 114, respectively. TSH receptor antibody (TRAb) was found negative and thyroid US did not reveal hypervascularity or nodules. Post admission TSH 0.544 and FT4 1.02 were found. The association between HG and thyrotoxicosis was made in 1980 by Valentine et al. Estrogen and hCG levels are significantly higher in women with HG, leading to increased thyroid hormone secretion and lower TSH levels. GTT resulting from inappropriate hCG secretion is a common form of hyperthyroidism in HG. GTT usually is described as an entity with spontaneous resolution as thyroid hormones normalize by the second trimester. Treatment for GTT with antithyroid drugs is not routinely indicated and they are reserved for a minority of patients with extremely severe GTT. Fasting, hydration, and evaluation of thyroid function are recommended as the most appropriate management for GTT in HG. Genetic mutations changing lysine into an asparagine leading to an increased sensitivity of TSH receptor to hCG ultimately causing severe and prolonged GTT have been found. TRAb is recommended as a more sensitive and specific diagnostic tool to differentiate GTT and Graves’ disease. However, physiological immunosuppression tends to suppress the TRAb levels during pregnancy. Comparative follow-up studies are required to establish a final diagnosis.