Thyroid Storm: Symptoms and Treatment
Thyroid storm is a life-threatening endocrine emergency characterized by fever, tachycardia disproportionate to fever, altered mental status, gastrointestinal symptoms, and cardiac arrhythmias—treatment must begin immediately without waiting for laboratory confirmation to prevent mortality. 1, 2
Clinical Presentation and Symptoms
Cardinal Features
- Fever with hyperthermia 1, 3
- Tachycardia disproportionate to the degree of fever 1, 2
- Altered mental status ranging from agitation to confusion or coma 1, 3
- Gastrointestinal symptoms including vomiting, diarrhea, and hepatic dysfunction 1, 3
- Cardiac manifestations including arrhythmias, signs of congestive heart failure, and potential cardiovascular collapse 1, 3
Additional Clinical Features
- Central nervous system disturbances beyond altered mental status 3
- Evidence of multiorgan decompensation including hepatic dysfunction 3, 4
- Acute heart failure as a common cause of death 4
Common Precipitating Factors
Thyroid storm typically occurs in the presence of an inciting trigger such as surgery, infection, labor, delivery, acute trauma to the thyroid gland, or severe emotional stress 2, 5. Even procedures like rapid sequence intubation can precipitate thyroid storm 5.
Diagnostic Approach
Laboratory Assessment
- Elevated free T4 or free thyroxine index with suppressed TSH supports the diagnosis, but no single laboratory value establishes thyroid storm 1
- Free T3 and the FT3/FT4 ratio may inversely correlate with disease severity, meaning severely ill patients may not have the highest thyroid hormone levels 1
- Do not delay treatment while awaiting laboratory confirmation, as mortality rises significantly with treatment delays 1, 2
Clinical Diagnostic Criteria
Two validated scoring systems exist: the Burch-Wartofsky point scale and Japan Thyroid Association diagnostic criteria 3. The key to diagnosis is considering the disease in the differential 3.
Important Mimics to Consider
Thyroid storm can mimic sympathomimetic overdose, substance use disorders, alcohol withdrawal, acute pulmonary edema, aortic dissection, heat stroke, serotonin syndrome, and sepsis/septic shock 3. Atypical presentations should be part of the differential diagnosis in patients with multiple organ dysfunction of unknown etiology 6.
Immediate Treatment Protocol
Initial Stabilization
- Immediately administer supplemental oxygen to stabilize the patient 1
- Position patient in head-up position to improve respiratory function 1
- Hospitalize all patients, with severe cases requiring ICU admission 1
Pharmacologic Treatment Algorithm (Sequential Order Matters)
Step 1: Block Thyroid Hormone Synthesis
- Administer propylthiouracil (PTU) as first choice because it inhibits both thyroid hormone synthesis AND peripheral T4 to T3 conversion 1, 2, 7
- Methimazole is an alternative option but only blocks new synthesis, not peripheral conversion 2
Step 2: Block Thyroid Hormone Release (Critical Timing)
- Administer saturated potassium iodide solution or sodium iodide 1-2 hours AFTER initiating thionamides 1, 2, 7
- Never administer iodine before thionamides, as this can worsen thyrotoxicosis by providing substrate for more hormone synthesis 2, 7
Step 3: Control Cardiovascular Symptoms
- Administer beta-blockers (propranolol preferred) to control tachycardia and cardiovascular symptoms 1, 2
- In cases of hemodynamic instability, consider short-acting beta-blockers like esmolol 7
- Non-dihydropyridine calcium channel blockers are alternatives if beta-blockers are contraindicated 2
- Caution: Avoid beta-blockers in severe heart failure 2
Step 4: Reduce Peripheral Hormone Conversion
- Administer dexamethasone or another corticosteroid to reduce peripheral conversion of T4 to T3 and treat potential relative adrenal insufficiency 1, 2, 7
Step 5: Supportive Care
- Provide oxygen therapy, antipyretics for hyperthermia, and appropriate monitoring 2
- Identify and treat precipitating factors (infection, surgery, trauma) 2
- Consider cholestyramine to enhance thyroid hormone elimination 3, 8
Monitoring and Complications
Critical Monitoring Parameters
- Increase frequency of observations for all patients with suspected thyroid storm 1
- Monitor for agranulocytosis with thionamide use 1, 2
- Watch for cardiac complications such as heart failure, which is a common cause of death 1, 2, 4
- Monitor thyroid function every 2-3 weeks after initial stabilization 1
Expected Clinical Course
- Watch for transition to hypothyroidism, which is common after thyroid storm treatment and may require initiation of levothyroxine replacement therapy 1
- Multiple organ failure is a common cause of death, requiring multidisciplinary critical care 4
Special Populations
Pregnancy
- Treatment protocol is similar to non-pregnant patients 2, 7
- Monitor fetal status throughout treatment 2, 7
- Avoid delivery during thyroid storm unless absolutely necessary 2, 7
Refractory Cases
For patients who inadequately respond to conventional therapies, therapeutic plasma exchange has been utilized successfully as a rescue treatment modality 8. Be prepared for rapid clinical deterioration and employ a multidisciplinary approach involving critical care and endocrinology specialists 3.
Definitive Management
After the acute crisis is controlled, plan definitive treatment of underlying thyrotoxicosis, which may include continued medical therapy, thyroidectomy, or radioactive iodine ablation 1, 2.