thyroid storm

see also:

• thyroid physiology and hormones
• hyperthyroidism
• Mx of a low TSH

• thyroid storm is a rare acute medical emergency with a high mortality if untreated
• occurs in 1-2% of hospitalized patients with hyperthyroidism
• 80% are women
• 80% are aged 20-50 years
• It is mostly seen in patients with Graves_disease and can be the first presentation of this, although it more commonly occurs in patients known to have hyperthyroidism who have not complied with medications or who have relapsed.

• classical signs:
  • fevers > 40degC (rarely, there may be no fever)
  • cardiac dysfunction (tachycardias with HR > 130, cardiac failure and potentially paradox weight gain due to fluid retention)
  • CNS dysfunction (restlessness, delirium, stupor, coma)
  • GIT symptoms (nausea, abdominal pain, diarrhoea, and jaundice)
• precipitating factors in patients with underlying hyperthyroidism include:
  • infections
  • emotional stress
  • surgical manipulation of thyroid gland
  • overdosage of thyroxine
  • body builder supplements containing liothyronine(T3) - will have low thyroglobulin levels - plus another precipitatant such as Coxsackie myopericarditis ¹⁾
  • administration of iodinated dyes
  • withdrawal of antithyroid drugs
  • administration of radioactive iodide
  • any acute illness, surgical procedure or trauma
  • acute cardiac illness eg. post-partum cardiomyopathy, Coxsackie myopericarditis

• “acute gastroenteritis”
• sepsis
• cardiac failure
• psychosis
• coma
• liver failure

• based upon clinical features in context of hyperthyroidism on thyroid function tests
• Burch-Wartofsky Point Scale
  • score below 25 is not suggestive of thyroid storm
  • score 25 to 45 suggests impending thyroid storm
  • score greater than 45 suggests current thyroid storm
  • see https://en.wikipedia.org/wiki/Thyroid_storm
• Japanese Thyroid Association (JTA) criteria²⁾
  • raised free T3 or T4, PLUS, EITHER:
    • at least one CNS manifestation and fever or tachycardia, or CHF or GI/hepatic manifestations, OR
    • at least three combinations of fever, or tachycardia, or CHF, or GI/hepatic manifestations, OR
    • “TS2”: combination of two of the following: fever or tachycardia or CHF or GI/hepatic manifestations
  • where fever = Temp more than 38degC; tachycardia = HR > 132; CHF = NYHA≥4 or Killip≥3; CNS = GCS≤14 or JCS≥1; GIT = N/V/D or jaundice (total bilirubin level more than 3.0 mg/dL)

• initial ED Rx of thyroid storm:
  • iv fluids
  • cooling
    • paracetamol
    • cooling blankets, etc
  • beta adrenergic blockers if no bronchospasm present:
    • usually propranolol 40-80mg po 4-6 hrly or 2-10mg iv 3-4hrly (max. rate 1mg/min)
    • alternatively, atenolol 25-100mg po daily or bd, or, metoprolol 25-50mg po qid
    • critically ill patients may be considered for iv infusion of esmolol 50-100 microg/kg/min
    • use with care if cardiac failure present
    • Since there is not sufficient beta-1 selectivity of the available beta-blockers at the recommended doses, these drugs are generally contraindicated in patients with bronchospastic asthma. However, in patients with quiescent bronchospastic asthma in whom heart rate control is essential, or in patients with mild obstructive airway disease or symptomatic Raynaud’s phenomenon, a nonselective beta-blocker such as nadolol can be used cautiously,with careful monitoring of pulmonary status. Calcium channel blockers, both verapamil and diltiazem, when administered orally and not intravenously, have been shown to effect rate control in patients who do not tolerate or are not candidates for beta-adrenergic blocking agents.³⁾
  • further Mx after endocrinology advice traditionally includes:
    • oral propylthiouracil (PTU) to block production T4
      • 500-1000mg load then 250mg 4hrly
      • NB. PTU now has a black box warning!
    • oral carbimazole to block hormone production
    • followed by iodine 5 drops (0.25ml or 250mg) po 6 hrly at least 1 hour after PTU to block secretion of T4
    • hydrocortisone 300mg iv load then 100mg 8hrly may be considered for Rx of associated adrenal insufficiency