II. Definitions
- Thyroid Storm
- Severe Thyrotoxicosis
III. Causes
- Uncontrolled Hyperthyroidism (esp. Graves Disease) with concurrent acute stress
- Pulmonary Infection (most common cause)
- Myocardial Ischemia or Myocardial Infarction
- Cerebrovascular Accident
- Trauma or surgery
- Gastrointestinal Illness
- Pregnancy (including Ectopic Pregnancy)
- Heat Illness
- Hypothermia
- Medications Affecting Thyroid Function (includes Drug-Induced Thyroiditis)
- Other, uncommon causes
- Graves Disease following Radioactive Iodine therapy
IV. Pathophysiology
- Up-regulation of Beta Adrenergic Receptors are more responsive to circulating Catecholamines (except in elderly)
- Even a seemingly minor trigger, may precipitate the appearance of a hyperadrenergic state
V. Precautions
- Elderly may present with minimal signs of Thyrotoxicosis (apathetic Thyroid Storm) with CHF, stupor to coma
- Cell surface Beta Adrenergic Receptors are present less in elderly and therefore decreased adrenergic response
- Have a low threshold for Thyroid testing in the elderly
- Young patients present more critically in Thyroid Storm
- Increased sensitivity to circulating Catecholamines results in severe, life-threatening presentations
VI. Symptoms
- See Hyperthyroidism
- Compared with typical Hyperthyroidism, Thyroid Storm presents more severe secondary symptoms
- Fever
- Altered Mental Status (e.g. Delirium)
- Dyspnea (including Orthopnea)
- Chest Pain
VII. Signs
- Fever >39 C (102 F)
- Hypertension
- Sinus Tachycardia or other tachydysrhythmia
- Profuse sweating
- High output cardiac failure (edema, pulmonary rales)
- Tachyarrhythmias (esp. Atrial Fibrillation)
- Altered Level of Consciousness (Delirium, Agitation or Psychosis)
VIII. Differential Diagnosis
IX. Associated Conditions
- New onset Atrial Fibrillation
- New onset, unexplained Congestive Heart Failure
X. Labs
-
Thyroid Stimulating Hormone (TSH)
- Suppressed in most cases
- Increased in TRH-Secreting Tumors (10-15% of Thyroid Storm cases)
-
Free T4
- Increased
- Broad based lab evaluation to cover differential diagnosis
- Comprehensive Metabolic Panel
- Liver Function Tests, Alkaline Phosphatase and Serum Calcium may be increased
- Complete Blood Count
- Pregnancy Test (bHCG) in women of child-bearing age
- Comprehensive Metabolic Panel
XI. Imaging
- Consider Chest XRay
- May demonstrate high output Heart Failure, precipitating events (e.g. Pneumonia)
XII. Diagnostics
-
Electrocardiogram
- Evaluate for Arrhythmia (e.g. Atrial Fibrillation, PSVT, Sinus Tachycardia)
XIII. Diagnosis
XIV. Management
-
General Measures
- Manage Airway
- Supplemental Oxygen
- Intravenous Fluids
- Dehydration may occur due to gastrointestinal loss, increased basal metabolic rate
- Cooling blanket and other external cooling
- Avoid active cooling due to worsening the Vasoconstriction already present with Thyroid Storm
- Use Acetaminophen for fever
- Avoid Salicylates and NSAIDS due to their increase of T4 and T3
- NSAIDS and Salicylates dislodge T4 from Protein binding and allow for conversion to the more active T3
- Treat concurrent infection (often inciting event)
- Thyroid Storm alone (without infection) can also result in fever, and distinguishing the two may be difficult
- Step 1: Heart Rate control (Beta Blockers are preferred)
- Beta Blockers (preferred)
- Beta Blockers slow rate AND decrease peripheral conversion from T4 to the more active T3
- Propranolol 10-20 mg IV every 4 hours (or 60 to 80 mg every 4 hours)
- Most common Beta Blocker used in Thyroid Storm
- Metoprolol 5-10 mg IV every 2-4 hours (or Metoprolol Tartrate 50 mg every 6 hours)
- Esmolol 50-100 mcg/kg/min IV
- Diltiazem (if Beta Blockers are contraindicated)
- Calcium Channel Blockers do not decrease peripheral conversion from T4 to the more active T3
- Diltiazem 0.25 mg/kg IV bolus over 2 min, then 10 mg/h IV (or 60-90 mg orally every 6-8 hours)
- Beta Blockers (preferred)
- Step 2: T4 and T3 Synthesis suppression with Thionamides
- Propylthiouracil (PTU) 200-400 mg every 8 hours PO, PR, or per NG
- Propylthiouracil is preferred in first trimester of pregnancy
- Most commonly used in Thyroid Storm, as it also decreases peripheral conversion of T4 to T3
- Methimazole 20-40 mg every 8 hours IV, PO, PR, per NG
- Methimazole is preferred in second and third trimesters of pregnancy
- Propylthiouracil (PTU) 200-400 mg every 8 hours PO, PR, or per NG
- Step 3: T4 and T3 Release suppression with Iodine
- Do NOT give before synthesis suppression (see step 2)
- May otherwise promote new Thyroid Hormone synthesis
- With all the focus on medication order in Thyroid Storm, this is the one critical step not to give too early
- Must only be given at least 30-60 minutes AFTER Thionamide (PTU or Methimazole)
- Iodine has two mechisms of action
- Increases Thyroid Hormone synthesis (worsening Thyroid Storm in absence of Thionamide)
- Blocks release of stored Thyroid Hormone and decreases Iodine transport
- Saturated Solution Potassium iodide (SSKI)
- Dose: 5 drops mixed in fluid or food every 6 hours for at least 2 days
- Initiate at least one hour after antithyroid medication
- Do NOT give before synthesis suppression (see step 2)
- Step 4: T4 to T3 conversion suppression with Glucocorticoids
- Preparations
- Hydrocortisone 100 mg IV every 8 hours OR
- Dexamethasone 2 mg orally or IV every 6 hours OR
- Betamethasone 0.5 mg orally, IV or IM every 6 hours
- Additional benefits of Corticosteroids (beyond T4 to T3 suppression)
- Also counters autoimmune process in Graves Disease
- Manages concurrent Adrenal Insufficiency
- Preparations
- Step 5: Apheresis
- Indicated in critically ill Thyroid Storm not responding to other measures
- In theory, removes from the serum, excess Thyroid Hormone
XV. Complications
- Atrial Fibrillation
-
Congestive Heart Failure
- Critical to distinguish between high output Heart Failure and low output Heart Failure
- Often related to secondary Atrial Fibrillation with Rapid Ventricular Rate (which improves with Beta Blockers)
-
Bedside Ultrasound
- Hyperdynamic heart activity is more consistent with high output Heart Failure
- Consider Non-Invasive Positive Pressure Ventilation (e.g. BIPAP)
- Avoid Diuretics (patients in Thyroid Storm are often hypovolemic)
XVI. References
- Swaminathan and Willis in Herbert (2019) EM:Rap 19(10): 13-5
- Swadron and Mason in Herbert (2019) EM:RAP C3 3(11): 1-10
- Carroll (2010) Ther Adv Endocrinol Metab 1(3): 139–145 [PubMed]
- Idrose (2015) Acute Med Surg 2(3): 147-57 +PMID: 29123713 [PubMed]
- Kravets (2016) Am Fam Physician 93(5): 363-70 [PubMed]
- Nayak (2006) Endocrinol Metab Clin North Am 35(4): 663-6 [PubMed]