What are the symptoms and treatment of thyroid storm?

Thyroid Storm: Symptoms and Treatment

Clinical Presentation

Thyroid storm is a life-threatening emergency characterized by the triad of hyperthermia, tachycardia, and altered mental status with severe agitation, always occurring with a precipitating trigger. 1

Cardinal Symptoms

• Fever/Hyperthermia - a defining feature that distinguishes storm from uncomplicated thyrotoxicosis 1, 2
• Cardiovascular manifestations including:
  • Tachycardia (often severe) 3, 1
  • Signs of congestive heart failure 3
  • Arrhythmias 3
• Central nervous system dysfunction with severe agitation, altered mental status, or decreased mentation 3, 1
• Gastrointestinal symptoms including vomiting, diarrhea, and hepatic dysfunction 3
• Myasthenia (muscle weakness) 2

Precipitating Factors

• Common triggers include infection, surgery, trauma, labor/delivery, iodine contamination, medication non-adherence, or radioactive iodine treatment 4, 1, 5

Important Diagnostic Caveat

• Laboratory values (TSH, free T4) do not differentiate thyroid storm from uncomplicated hyperthyroidism - the diagnosis is purely clinical based on multiorgan decompensation 2
• Clinical scoring systems include the Burch-Wartofsky point scale and Japan Thyroid Association criteria 3

Treatment Algorithm

Immediate Actions (Do Not Wait for Labs)

Treatment must begin immediately based on clinical suspicion, as mortality rises significantly with delays and can reach 75% without prompt intervention. 4

Step 1: Block Thyroid Hormone Synthesis (First)

• Administer propylthiouracil (PTU) first - 500-1000 mg loading dose, then 250 mg every 4 hours, as it uniquely blocks both synthesis AND peripheral T4 to T3 conversion 4
• Alternative: Methimazole 20 mg every 4-6 hours if PTU unavailable (though lacks peripheral conversion blocking) 4

Step 2: Block Thyroid Hormone Release (1-2 Hours After Step 1)

• Wait 1-2 hours after starting thionamides before giving iodine to prevent iodine from being used as substrate for new hormone synthesis 4
• Saturated solution of potassium iodide (SSKI) 5 drops every 6 hours, OR 4
• Sodium iodide 500-1000 mg IV every 8 hours, OR 4
• Lugol's solution as alternative 4
• Lithium if iodine contraindicated 4

Step 3: Block Peripheral Conversion and Cardiovascular Effects

• Propranolol 60-80 mg orally every 4-6 hours is first-line because it also blocks peripheral T4 to T3 conversion 4
• For hemodynamically unstable patients requiring vasopressors: Use esmolol with loading dose 500 mcg/kg IV over 1 minute, then maintenance infusion starting at 50 mcg/kg/min, titrating up to maximum 300 mcg/kg/min 4
• Avoid beta-blockers in severe heart failure 4
• If beta-blockers contraindicated: Diltiazem 15-20 mg (0.25 mg/kg) IV over 2 minutes, then 5-15 mg/h maintenance infusion 4

Step 4: Additional Hormone Blockade

• Dexamethasone 2 mg IV every 6 hours to reduce peripheral T4 to T3 conversion 4
• Cholestyramine to bind thyroid hormones in enterohepatic circulation 2

Step 5: Aggressive Supportive Care

• Oxygen therapy as needed 4
• Antipyretics for fever control (AVOID ASPIRIN as it increases free thyroid hormone levels) 4
• Aggressive fluid resuscitation with large-bore IV access 4
• Identify and treat precipitating factors (infection, trauma, etc.) 4

Step 6: Hospitalization and Monitoring

• All patients require hospitalization; severe cases need ICU admission 4
• Obtain immediate endocrinology consultation 4
• Monitor for cardiac complications including heart failure and arrhythmias 4
• Monitor for agranulocytosis with thionamide use (presents with sore throat and fever) 4
• Be prepared for rapid clinical deterioration requiring multidisciplinary critical care approach 3

Special Populations: Pregnancy

• Treatment protocol is identical to non-pregnant patients 4
• Monitor fetal status with ultrasound, nonstress testing, or biophysical profile based on gestational age 4
• Avoid delivery during thyroid storm unless absolutely necessary due to high maternal and fetal mortality risk 4
• Thyroid storm affects less than 1% of pregnant women with hyperthyroidism but carries exceptionally high risk 4

Follow-Up Care

• Monitor thyroid function every 2-3 weeks after initial stabilization 4
• Watch for transition to hypothyroidism, which commonly occurs after thyroid storm treatment 4

Key Pitfalls to Avoid

• Never wait for laboratory confirmation - clinical diagnosis and immediate treatment are essential 4
• Never give iodine before thionamides - this can paradoxically worsen hormone synthesis 4
• Never use aspirin for fever - it displaces thyroid hormone from binding proteins 4
• Consider mimics including sympathomimetic overdose, alcohol withdrawal, septic shock, serotonin syndrome, and heat stroke 3