Gestational transient thyrotoxicosis is common rarely requiring treatment. We present a rare case of impending thyroid storm from a partial hydatidiform mole requiring medical and surgical intervention.
A 19 year old woman 15 weeks gestation presented with nausea, vomiting, vaginal bleeding, back/abdominal pain, anxiety and palpitations. Tachycardia was present (135 bpm), temp 37.6 C, blood pressure 125/85. Thyroid was not enlarged with no bruit. Fetal tachycardia was present (227 bpm). Transvaginal ultrasound showed an abnormal fetus with a large amount of fluid in the brain consistent with a partial molar pregnancy. Initial studies showed beta human chorionic gonadotropin (ß-hCG) greater than 1,333,863 mIU/mL,TSH 0.007 mcIU/mL and Free T4 2.43 ng/dL. Patient scored 45 on the Burch-Wartofsky Point Scale (BWPS) highly suggestive of impending thyroid storm. Propranolol and propylthiouracil (PTU) were started in preparation for surgery. Molar pregnancy was evacuated and ß-hCG decreased.
Impending thyroid storm from a partial molar pregnancy is rare. Gestational trophoblastic disease (GTD), is a rare complication of pregnancy. Molar pregnancy incidence is 1 in 1500 live births in the United States with hyperthyroidism in 25 - 64% of cases. Despite elevated thyroid hormone levels overt clinical thyrotoxicosis is uncommon. Patients with a molar pregnancy rarely require medical intervention prior to dilatation and evacuation. The trophoblast or outer layer of the fertilized egg, differentiates and invades into the endometrium and uterine vasculature to form the placenta and secrete ß-hCG. Normally ß-hCG decreases to less than one fifth of the peak first trimester levels as the pregnancy progresses. In contrast, in partial molar pregnancies ß-hCG increases approximately 4% due to ß-hCG deregulation. ß-hCG has thyroid stimulating hormone activity and is estimated that “for every 10,000 mU/mL increase in serum ß-hCG, free T4 increases by 0.1 ng/dL and TSH decreases by 0.1 uIU/mL”. In our patient the free T4 is less than expected by this algorithm and TSH receptor sensitivity and ß-hCG variants may be responsible for the patient’s symptoms and the lesser rise in Free T4 levels. Patients should be evaluated for thyrotoxicosis upon diagnosis of a molar pregnancy.
Evacuation of the molar pregnancy is the recommended treatment and thionamides should be considered to avoid thyroid storm at anesthesia induction or post operatively. Elevated ß-hCG levels should return to normal in two to three months. Thyroid hormone levels should return to the patient’s previous status.
First Year Endocrinology fellow
First year endocrinology fellow
Program Director on Endocrinology fellowship
Program director with interest in thyroid.