What is the treatment for a thyroid storm in a pregnant patient?

Thyroid Storm in Pregnancy: Treatment Protocol

Immediate Multi-Drug Therapy (Do Not Wait for Laboratory Confirmation)

Initiate treatment immediately based on clinical diagnosis—mortality rises significantly with delays, and laboratory confirmation should never postpone therapy. 1, 2

First-Line Thionamide Therapy

• Administer propylthiouracil (PTU) as the first-line agent in pregnancy, as it blocks both thyroid hormone synthesis AND peripheral T4 to T3 conversion—a critical advantage over methimazole. 3, 2, 4
• PTU dosing: Standard loading dose followed by maintenance dosing every 4-6 hours. 1
• Methimazole 20 mg every 4-6 hours can be used as an alternative if PTU is unavailable, though it lacks the peripheral conversion blocking effect. 2
• Critical timing: Never administer iodine before starting thionamides, as iodine provides substrate for new hormone synthesis and will worsen the crisis. 3

Iodine Administration (1-2 Hours AFTER Thionamides)

• Administer saturated solution of potassium iodide (SSKI) 5 drops every 6 hours, OR sodium iodide 500-1000 mg IV every 8 hours. 1, 2
• Alternative options if iodine contraindicated: Lugol's solution or lithium. 1, 2
• This 1-2 hour delay after thionamides is mandatory to prevent providing substrate for accelerated hormone synthesis. 2

Beta-Blocker Therapy

• Propranolol 60-80 mg orally every 4-6 hours is the preferred beta-blocker because it also blocks peripheral T4 to T3 conversion beyond rate control. 3, 2
• For hemodynamically unstable patients: Esmolol with loading dose of 500 mcg/kg IV over 1 minute, then maintenance infusion starting at 50 mcg/kg/min, titrating up to maximum 300 mcg/kg/min. 1, 2
• Aggressive treatment with high-dose IV beta-blockers is particularly important in thyroid storm, as standard doses may be insufficient. 1
• If beta-blockers contraindicated (severe heart failure): Use diltiazem 15-20 mg (0.25 mg/kg) IV over 2 minutes, then 5-15 mg/h maintenance infusion. 1, 2

Corticosteroid Administration

• Dexamethasone 2 mg IV every 6 hours to reduce peripheral T4 to T3 conversion and address potential adrenal insufficiency. 1, 3, 2
• This addresses both the conversion pathway and the stress-induced relative adrenal insufficiency that accompanies thyroid storm. 1

Essential Supportive Care

• Oxygen therapy as needed. 1, 2
• Antipyretics for fever control (avoid aspirin, as it increases free thyroid hormone levels). 2
• Aggressive fluid resuscitation with large-bore IV access. 2
• Identify and treat precipitating factors: infection, surgery, trauma, labor/delivery, or medication non-adherence. 1, 2

Pregnancy-Specific Management Considerations

The treatment protocol for thyroid storm is identical to non-pregnant patients—do not modify the multi-drug regimen. 3, 2

Fetal Monitoring

• Monitor fetal status with ultrasound examination, nonstress testing, or biophysical profile based on gestational age. 1, 3, 2
• Avoid delivery during thyroid storm unless absolutely necessary, as maternal and fetal mortality risk is extremely high during active crisis. 1, 3, 2
• Thyroid storm affects less than 1% of pregnant women with hyperthyroidism but carries high maternal and fetal risk including heart failure, preeclampsia, preterm delivery, miscarriage, and intrauterine fetal demise. 3, 2, 5, 6

Anticoagulation Considerations

• Administer antithrombotic therapy (anticoagulant or aspirin) throughout pregnancy to all patients with atrial fibrillation complicating thyrotoxicosis, except those with lone AF. 1
• Heparin is the preferred anticoagulant in pregnancy, as warfarin crosses the placental barrier and causes teratogenic embryopathy in the first trimester and fetal hemorrhage later. 1
• The value of subcutaneous unfractionated heparin or low-molecular-weight heparin in preventing stroke has not been proven in AF patients, but use is based on experience with prosthetic valves and venous thromboembolism. 1

Hospitalization and Monitoring Requirements

• All patients require hospitalization; severe cases need ICU admission. 2
• Obtain immediate endocrinology consultation. 2
• Monitor for cardiac complications including heart failure and arrhythmias. 1, 2
• Monitor for agranulocytosis with thionamide use (presents with sore throat and fever)—this is a life-threatening complication requiring immediate drug discontinuation. 2, 4, 7
• Monitor prothrombin time, as propylthiouracil may cause hypoprothrombinemia and bleeding, especially before surgical procedures. 4

Critical Pitfalls to Avoid

• Never delay treatment waiting for thyroid function tests—clinical diagnosis is sufficient, and mortality rises dramatically with delays. 1, 3, 2
• Never administer iodine before thionamides, as this provides substrate for new hormone synthesis and worsens the crisis. 3
• Never use radioactive iodine (I-131) during pregnancy—it is absolutely contraindicated and causes fetal thyroid ablation. 1, 3
• Do not use aspirin for fever control, as it displaces thyroid hormone from binding proteins and increases free hormone levels. 2
• Electrical cardioversion can be performed without fetal damage if hemodynamic embarrassment occurs with atrial fibrillation. 1

Follow-Up After Stabilization

• Monitor thyroid function every 2-3 weeks after initial stabilization. 2
• Watch for transition to hypothyroidism, which commonly occurs after thyroid storm treatment. 2
• Once clinical evidence of hyperthyroidism resolves, an elevated serum TSH indicates that a lower maintenance dose of propylthiouracil should be employed. 4