Thyroid storm

Definition

Thyroid storm is a rare, life-threatening exacerbation of thyrotoxicosis with hypermetabolism and dysfunction of multiple organ systems. It is a clinical diagnosis: no hormone level reliably separates it from severe but uncomplicated thyrotoxicosis.

Occurrence & epidemiology

Thyroid storm is rare; its exact frequency is hard to determine because criteria vary. Among patients in hospital with severe thyrotoxicosis, it accounts for about 10–16 %.

Aetiopathogenesis

Underlying disease: most commonly Graves' disease, also toxic multinodular goiter, less often destructive thyroiditis; a solitary toxic adenoma is a less common cause and usually leads to milder courses.

Risk factors: older age, long-standing or poorly controlled hyperthyroidism, irregular intake of antithyroid drugs.

Precipitating factors: infection, perioperative stress, trauma, myocardial infarction, stroke, childbirth, diabetic ketoacidosis, preeclampsia, embolism and iodinated contrast media.

Pathophysiology: hormone levels often do not differ from those in uncomplicated thyrotoxicosis. Proposed mechanisms include increased tissue sensitivity to catecholamines, activated inflammatory cytokines, predominance of T3 effects at tissue level and changes in hormone binding and cellular uptake.

Clinical features

• Fever, usually above 38.5 °C
• Cardiovascular: tachycardia disproportionate to the fever, arrhythmias (particularly atrial fibrillation), heart failure with pulmonary edema up to cardiogenic shock
• Central nervous system: extreme restlessness and agitation, emotional lability, delirium, psychosis, lethargy up to coma, seizures
• Gastrointestinal and liver: nausea, vomiting, diarrhea, abdominal pain, hepatomegaly and jaundice
• Muscles: marked weakness and muscle wasting

Older people may present in an "apathetic" way, with little tachycardia, hardly any agitation and nonspecific complaints.

Diagnosis

Burch-Wartofsky Point Scale

• Temperature: 38–38.5 °C 5 points; 38.6–39 °C 10; 39.1–39.5 °C 15; 39.6–40 °C 20; 40.1–40.6 °C 25; > 40.6 °C 30
• Central nervous system: mild (agitation) 10; moderate (delirium, psychosis, extreme lethargy) 20; severe (seizure, coma) 30
• Gastrointestinal and hepatic: moderate (diarrhea, abdominal pain, nausea, vomiting) 10; severe (jaundice) 20
• Heart rate per minute: 90–109 5; 110–119 10; 120–129 15; 130–139 20; ≥ 140 25
• Heart failure: mild (pedal edema) 5; moderate (bibasilar crackles) 10; severe (pulmonary edema) 15
• Atrial fibrillation: 10
• Precipitating event: 10

Interpretation: < 25 points makes storm unlikely, 25–44 points suggest impending storm, ≥ 45 points are highly suggestive.

Japanese Thyroid Association criteria

Biochemically confirmed thyrotoxicosis (raised fT3 and/or fT4) is a prerequisite. CNS symptoms, fever ≥ 38 °C, tachycardia ≥ 130/min, heart failure and gastrointestinal or hepatic involvement (including total bilirubin ≥ 3 mg/dl) are assessed.

• Definite storm (TS1): at least one CNS symptom plus one further feature, or at least three of the non-CNS features
• Suspected storm (TS2): two of the non-CNS features

Neither scale has been validated against a gold standard. The Burch-Wartofsky Point Scale overlaps with severe uncomplicated cases; in critically ill patients with sepsis, fever and tachycardia can lead to overdiagnosis.

Further work-up

• Thyroid function: TSH suppressed, fT4 and fT3 raised; the level does not distinguish storm from uncomplicated thyrotoxicosis
• Organ involvement: ECG (tachycardia, atrial fibrillation), liver enzymes and bilirubin, kidney function, glucose, electrolytes
• Cause and trigger: TSH receptor antibodies, thyroid ultrasound; targeted search for infection, myocardial infarction or other triggers

Keep learning in the app

Further reading (open access)

1. Eur Thyroid J 2026: Joint consensus statement on thyroid storm (ETA, BTA, SfE, WEDS)
2. MSD Manual Professional: Hyperthyroidism (Thyroid storm)

Cross-references