Thyroid Storm

Thyroid storm is also known as thyroid crisis.

Clinical diagnosis of thyrotoxicosis of life-threatening severity, which classically presents with a combination of adrenergic symptoms:

This covers thyroid storm; considerations of general hyperthyroidism are covered at Hyperthyroidism.

Epidemiology and Risk Factors

Pathophysiology

Aetiology

Precipitants include:

  • Cessation of usual thyroid suppression
  • Thyroid hormone overdose
  • Iodinated contrast
  • Physiological stress
    • Infection
    • Trauma
      • Surgery
      • Burns
    • DKA
    • CVA
  • Excessive thyroid palpation

Clinical Manifestations

Extremely variable presentation, with all or some of:

  • B
    • Dyspnoea
  • C
    • ↑ HR
    • Tachyarrhythmias
      • AF
      • Ventricular arrhythmias
    • Heart failure
    • ↑ BP (early)
    • ↓ BP (late)
  • D
    • Tremor → Weakness
      Generally early signs.
    • Encephalopathy → Coma
  • E
    • Fever
  • G
    • Diarrhoea
    • Nausea
    • Vomiting
    • Jaundice

Diagnostic Approach and DDx

Key differentials include:

  • Sepsis
  • Anticholinergic toxicity

Investigations

Bedside:

  • ABG/VBG
    • ↑ BSL

Laboratory:

  • FBE
    • Leucocytosis
  • UEC
    • Hypercalcaemia
    • Hypokalaemia
    • Hypomagnesaemia
  • LFTs
    • ↑ Bilirubin
  • Cortisol
    Should be ↑ in the setting of thyroid storm, and requires corticosteroids otherwise.
  • TFTs
    • TSH usually undetectable
    • Free T4 and T3 usually ↑

TFTs do not correlate with clinical severity.

Imaging:

Other:

Management

  • Control adrenergic symptoms
  • Correct thyroid abnormalities
  • Treat precipitating cause

Resuscitation:

  • C
    • β-blockade
      • Propranolol
        Agent of choice for cardiovascular symptoms.
        • 0.5-1mg IV increments for acute control
        • 60-120mg Q4-6H for maintenance
      • Esmolol
        Alternative for rapid, titrateable control.
    • Amiodarone
      • 2nd line agent for arrhythmias
      • Also inhibits T4 conversion
      • May interfere with TFT measurement and so confound future therapy
    • Volume resuscitation
      • Patients generally undervolumed
        Diarrhoea, vomiting, insensible losses.
      • Resuscitation must be cautious in the setting of cardiac failure

Propranolol is preferred to other β-blockers because it also ↓ peripheral conversion of T4 to T3. High doses are required due to ↑ elimination that occurs during a thyroid storm.

Specific therapy:

  • Pharmacological
    • Corticosteroids
      • ↓ T4 conversion
      • Correct adrenal insufficiency
    • Thionamides
      Inhibit thyroid hormone synthesis.
      • Propylthiouracil
        Preferred agent.
        • 200mg PO Q4H
    • Iodine
      Inhibit thyroid hormone release.
      • Must be given after thionamide, otherwise it will ↑ hormone synthesis and worsen thyrotoxicosis
      • 1g sodium iodide IV Q12H
      • Iodinated contrast media may be used as an alternative

Supportive care:

  • E
    • Cooling
      • Passive cooling usually adequate
  • G
    • Feeding
      Usually caloric deficient, consider early feeding.

Disposition:

  • Thyroid storm necessitates ICU admission

Preventative:

Marginal and Ineffective Therapies

Non-established therapies include:

  • Plasmapheresis
  • Charcoal haemoperfusion
  • Dantrolene

Anaesthetic Considerations

Complications

  • E
    • Rhabdomyolysis

Prognosis

Key Studies

References

  1. Bersten, A. D., & Handy, J. M. (2018). Oh’s Intensive Care Manual. Elsevier Gezondheidszorg.