Harvey's Garden

Thyroid storm

3 min read

A rare, life-threatening exacerbation of hyperthyroidism, characterized by acute, severe multisystem decompensation. It is a medical emergency with a mortality rate of 8-25%.

  • Pathophysiology/Etiology

    • An acute, severe release of thyroid hormones in a patient with underlying thyrotoxicosis (often undiagnosed or undertreated Graves’ disease).
    • Precipitating factors are key and include: infection (most common), surgery, trauma, abrupt withdrawal of antithyroid drugs, parturition (childbirth), and iodinated contrast media.

  • Clinical Presentation

    • Hyperthermia: High fever (often >40°C / 104°F) with diaphoresis is a hallmark sign.
    • Cardiovascular: Sinus tachycardia (often >140 bpm), atrial fibrillation, high-output heart failure, and hypertension followed by hypotension/shock.
    • CNS: Agitation, delirium, psychosis, seizures, and progression to stupor or coma.
    • GI/Hepatic: N/V, diarrhea, abdominal pain, and jaundice (a poor prognostic sign).
    • Apathetic thyrotoxicosis, a rare variant seen in the elderly, may present with apathy, weakness, and confusion without a significant fever.

  • Diagnosis

    • Primarily a clinical diagnosis; treatment should not be delayed for lab confirmation.
    • Burch-Wartofsky Point Scale: A scoring system that can help predict the likelihood of thyroid storm based on the severity of symptoms (temp, CNS, CV, and GI dysfunction). A score >45 is highly suggestive.
    • Lab Findings:
      • Suppressed TSH with elevated free T4 and/or T3.
      • Other findings may include hyperglycemia, hypercalcemia, and abnormal LFTs.

  • Differential Diagnosis (DDx)

    • Sepsis: Overlapping features of fever, tachycardia, and altered mental status.
    • Pheochromocytoma: Presents with paroxysmal hypertension, palpitations, and diaphoresis.
    • Malignant Hyperthermia: Associated with exposure to volatile anesthetics or succinylcholine.
    • Neuroleptic Malignant Syndrome: Linked to antipsychotic use; features rigidity and hyperthermia.
    • Anticholinergic/Cocaine Toxicity: Can cause agitation, tachycardia, and hyperthermia.

  • Management/Treatment A multi-step approach is critical:

    1. Beta-Blockers (e.g., Propranolol): First-line to control adrenergic symptoms (tachycardia, agitation). Propranolol also helps block the peripheral conversion of T4 to T3.
    2. Thionamides (Antithyroid Drugs): Block new hormone synthesis. Propylthiouracil (PTU) is often preferred as it also inhibits peripheral T4 to T3 conversion. Methimazole (MMI) is an alternative.
    3. Iodine Solution (e.g., SSKI, Lugol’s solution): Administer at least 1 hour after the thionamide to block the release of pre-formed thyroid hormone (Wolff-Chaikoff effect).
    4. Glucocorticoids (e.g., Hydrocortisone, Dexamethasone): Reduce peripheral T4 to T3 conversion and provide proactive support for potential relative adrenal insufficiency.
    5. Supportive Care: Aggressive cooling with cooling blankets and acetaminophen (avoid aspirin as it can displace thyroid hormone from binding proteins), IV fluids, and treatment of any underlying precipitant.

  • Complications & Key Associations

    • Most commonly associated with Graves’ disease.
    • Complications include high-output heart failure, arrhythmias, multi-organ failure, and DIC.
    • Mortality is high if untreated; however, most patients show clinical improvement within 24 hours with aggressive therapy.

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