Graves Hyperthyroidism and Pregnancy: A Clinical Update

Komal Patil-Sisodia, MD; Jorge H. Mestman, MD


Endocr Pract. 2010;16(1):118-129. 

In This Article

Maternal Complications

Maternal complications (Table 5) are directly related to control of hyperthyroidism. Pregnancy-induced hypertension is the most common complication of maternal hyperthyroidism. The risk of severe preeclampsia is increased 5-fold in women with poorly controlled hyperthyroidism.[44] Uncontrolled hyperthyroidism in pregnancy is also associated with premature delivery, low birth weight, placenta abruptio, and spontaneous abortions. Congestive heart failure is another complication that may be seen in hyperthyroidism. Women with cardiac symptoms should have evaluation of left ventricular function by serial echocardiograms, which can detect dysfunction of different degrees of severity. Left ventricular function returns to normal several weeks after serum T4 normalizes.[45] Despite the normalization of left ventricular function with return to euthyroidism, cardiac output remains elevated and peripheral vascular resistance reduced. When affected women undergo tremendous stress, such as preeclampsia or cesarean delivery, their condition may decompensate further. Judicious use of intravenous fluid with close observation is recommended.[46] Thyroid storm is an extremely rare and life-threatening complication of maternal hyperthyroidism and is discussed in a separate section that follows.

Thyroid Storm

Thyrotoxic crisis is an extremely rare and lifethreatening complication of hyperthyroidism that occurs in patients with poorly controlled or untreated disease. Between 1% and 2% of hyperthyroid women experience thyroid storm in pregnancy.[47] Precipitating events such as infection, trauma, surgery, diabetic ketoacidosis, toxemia in pregnancy, placenta previa, and induction of labor can cause development of thyroid storm. The diagnosis of this entity is a clinical one. To diagnose thyroid storm, the patient must have the following: (a) severe thyrotoxicosis on clinical examination (tachycardia, tremors, and heat intolerance), (b) altered mental status, and (c) hyperpyrexia (temperature greater than 103°F). Additionally, patients may have cardiac manifestations such as tachyarrhythmias (atrial fibrillation and atrial flutter) with pulse rates exceeding 140 beats/min and congestive heart failure. They may also present with nonspecific gastrointestinal symptoms such as nausea and vomiting, as well as liver compromise. On laboratory testing, TSH is suppressed and T4 values are elevated, although the degree of change in T4 concentration does not correlate with disease severity.

Thyroid storm is best managed in the intensive care unit. Patients should receive intravenous fluids and electrolyte repletion in a monitored setting and be observed for altered mental status or respiratory compromise. Medical therapy of thyroid storm consists of the following: (a) β-adrenergic blockers for control of hyperadrenergic symptoms, (b) PTU (recommended over methimazole because of the ability to block the metabolism of T4 to T3) with a switch to methimazole after the clinical picture improves, (c) Lugol's solution or super-saturated potassium iodide, and (d) glucocorticoids. β-Adrenergic blockers can be given either orally or intravenously in the form of propranolol, 60 to 80 mg by mouth every 4 hours or 1 mg/min via intravenous drip. Esmolol, a short-acting β-acting antagonist given intravenously, may be used starting with a loading dose of 250 to 500 mcg/kg of body weight followed by continuous infusion of 50 to 100 mcg/kg per min. Obtaining pan-cultures, performing a chest x-ray, and starting broad-spectrum intravenous antibiotics is prudent because infection is one of the most common precipitating events. From a fetal perspective, close obstetric monitoring is also necessary. Assessment of fetal well-being through fetal heart rate monitoring and other techniques should be performed during the acute phase of the disease. Thyroid storm is a life-threatening condition for both the mother and the fetus. Early diagnosis and aggressive, multifaceted treatment in an intensive care setting help decrease the morbidity and mortality associated with this condition.