What is the treatment for thyroid storm in pregnancy?

Treatment of Thyroid Storm in Pregnancy

The treatment of thyroid storm in pregnancy requires immediate intervention with a standard series of medications including propylthiouracil, saturated solution of potassium iodide or sodium iodide, dexamethasone, and beta-blockers, along with supportive care to prevent maternal heart failure and fetal complications. 1

Diagnosis

Thyroid storm in pregnancy is a clinical diagnosis based on:

• Fever
• Tachycardia disproportionate to fever
• Altered mental status (nervousness, restlessness, confusion, seizures)
• Gastrointestinal symptoms (vomiting, diarrhea)
• Cardiac arrhythmias

An inciting event such as surgery, infection, labor, or delivery may be identified. Laboratory confirmation with FT3, FT4, and TSH levels is helpful but treatment should not be delayed awaiting results. 1

Treatment Algorithm

Step 1: Immediate Pharmacological Intervention

• Thionamides: Propylthiouracil (PTU) is preferred in the first trimester due to lower risk of teratogenicity 2, 3

  • PTU inhibits both thyroid hormone synthesis and peripheral conversion of T4 to T3, making it particularly effective for thyroid storm 3
  • Typical dose: 200-400 mg orally every 4-6 hours

• Iodide solution: Administer 1-2 hours after thionamide (to prevent iodine utilization for thyroid hormone synthesis)

  • Options include saturated solution of potassium iodide, sodium iodide, or Lugol's solution
  • Alternative: Lithium if iodide is contraindicated 1

• Corticosteroids: Dexamethasone

  • Inhibits peripheral conversion of T4 to T3
  • Addresses potential relative adrenal insufficiency

• Beta-blockers: Control cardiovascular symptoms

  • For patients with history of severe bronchospasm, consider alternatives: reserpine, guanethidine, or diltiazem 1
  • Propranolol is commonly used but esmolol may be preferred for its shorter half-life 4

• Sedation: Phenobarbital may be used to control agitation 1

Step 2: Supportive Care

• Oxygen administration
• Antipyretics for fever management
• Fluid and electrolyte management
• Continuous cardiac monitoring
• Treatment of the precipitating cause (infection, etc.) 1

Step 3: Fetal Assessment and Monitoring

• Ultrasound examination
• Nonstress testing
• Biophysical profile
• Avoid delivery during thyroid storm unless absolutely necessary 1

Special Considerations

Medication Adjustments

• Propylthiouracil: Crosses the placenta but is preferred in the first trimester; consider switching to methimazole in second and third trimesters due to risk of PTU-associated hepatotoxicity 2, 3
• Beta-blockers: May require dose adjustment as hyperthyroidism increases clearance 3
• Monitoring: Check prothrombin time as PTU may cause hypoprothrombinemia and bleeding 3

Potential Complications

• Maternal heart failure is a significant risk 1, 2
• Untreated thyroid storm can progress to shock, stupor, and coma 1
• Fetal complications include preterm birth, intrauterine growth restriction, and fetal death 5, 6
• Maternal mortality rate exceeds 10% even with treatment 5

Pitfalls to Avoid

1. Delayed recognition: Thyroid storm is a clinical diagnosis; do not wait for laboratory confirmation before initiating treatment 1, 7

2. Inadequate medication dosing: Aggressive treatment with high-dose thionamides is necessary 1

3. Using medications that exacerbate symptoms: Avoid drugs that excite sympathetic nerves or promote histamine release during cesarean section if hyperthyroidism is suspected 4

4. Overlooking the precipitating cause: Identify and treat the underlying trigger (infection, trauma, etc.) 8

5. Premature delivery: Unless absolutely necessary, avoid delivery during active thyroid storm 1

Thyroid storm in pregnancy represents a true medical emergency requiring prompt recognition and aggressive treatment to prevent significant maternal and fetal morbidity and mortality. A coordinated multidisciplinary approach involving endocrinology, obstetrics, and critical care is essential for optimal outcomes.