Thyroid Storm
Life-threatening exacerbation of thyrotoxicosis with multi-organ decompensation. Mortality ~10-30% even with treatment. Typically precipitated by infection, surgery, or trauma in uncontrolled hyperthyroidism. Characterised by high fever, tachycardia, agitation, and organ failure. Requires emergency multi-modal treatment.
Key Facts
Medical emergency: mortality ~10-30%; severe thyrotoxicosis with multi-organ dysfunction (cardiovascular, thermoregulatory, CNS, GI, hepatic) Precipitants: infection (commonest), surgery (especially thyroid surgery in unprepared patient), trauma, DKA, MI, drug withdrawal, radioiodine, iodinated contrast Clinical features: high fever (>38.5°C), severe tachycardia/AF/heart failure, agitation/delirium/psychosis/coma, nausea/vomiting/diarrhoea/jaundice, tremor, sweating Burch-Wartofsky Point Scale (BWPS): scoring system; >45 = thyroid storm likely; 25-44 = impending; <25 = unlikely Treatment (multi-modal, simultaneous): propylthiouracil 200mg QDS (blocks synthesis + T4→T3 conversion) or carbimazole 20-40mg QDS; Lugol iodine (1 hour after ATD — blocks thyroid hormone release); propranolol 40-80mg QDS (rate control, T4→T3 conversion); IV hydrocortisone 100mg QDS (reduces T4→T3, prevents adrenal crisis); supportive: cooling, IV fluids, treat precipitant
Overview
Key Facts
Thyroid storm is a clinical diagnosis based on the Burch-Wartofsky scale. Multi-modal treatment must be started immediately. The order of drug administration matters — give ATD before iodine.
Epidemiology
Rare: <2% of thyrotoxic patients. More common in Graves disease. Mortality ~10-30% even with treatment (higher in elderly, delayed treatment).
Aetiology
Almost always occurs on a background of uncontrolled/poorly treated hyperthyroidism with an acute precipitant: infection, surgery, trauma, DKA, MI, iodinated contrast, radioiodine, drug withdrawal.
Pathophysiology
Massive thyroid hormone excess → adrenergic hyperstimulation → multi-organ decompensation. Exact mechanism unclear — T4/T3 levels may not be dramatically higher than uncomplicated thyrotoxicosis; likely involves enhanced tissue sensitivity, cytokine surge, and precipitant-related stress response.
Clinical Presentation
Cardinal Features
- Fever: high (>38.5°C, often >40°C); diaphoresis
- Cardiovascular: severe tachycardia (>140 bpm), AF, high-output heart failure, hypotension/shock
- CNS: agitation, delirium, psychosis, seizures, coma
- GI: nausea, vomiting, diarrhoea, abdominal pain, jaundice (hepatic dysfunction — ominous sign)
Burch-Wartofsky Point Scale
- Temperature, CNS effects, GI/hepatic, cardiovascular (HR, HF, AF) scored
-
45 points = highly suggestive of thyroid storm
Red Flags
- Multi-organ failure
- Jaundice/hepatic dysfunction (poor prognostic sign)
- Coma
- Cardiovascular collapse
Differential Diagnosis
| Diagnosis | Key Features | Investigation |
|---|---|---|
| Sepsis | Fever, source of infection, raised lactate | Cultures, lactate |
| NMS | Antipsychotic exposure, rigidity, raised CK | Drug history, CK |
| Malignant hyperthermia | Post-anaesthesia, rigidity, raised CK | Genetic testing |
| Phaeochromocytoma crisis | Paroxysmal HTN, headache, sweating | Plasma metanephrines |
| Heat stroke | Environmental exposure, CNS dysfunction | History |
Diagnosis / Investigation
Immediate
- TFTs: suppressed TSH, markedly elevated T4/T3 (but may not be dramatically different from uncomplicated thyrotoxicosis)
- FBC, U&Es, LFTs, coagulation, glucose, calcium
- Blood cultures, urine cultures, CXR: identify precipitant
- ECG: tachycardia, AF
- ABG: metabolic/respiratory alkalosis or mixed
Burch-Wartofsky Scoring
- Clinical scoring system to support diagnosis
Management
Emergency Multi-Modal Treatment (Simultaneous)
-
Antithyroid drugs (block new hormone synthesis):
- PTU 200mg QDS PO/NG preferred (also blocks peripheral T4→T3 conversion)
- Alternative: carbimazole 20-40mg QDS PO/NG
-
Iodine (blocks thyroid hormone release — give ≥1 HOUR after ATD):
- Lugol iodine 5-10 drops TDS PO/NG
- Or potassium iodide 60mg TDS
-
Beta-blockers (rate control + T4→T3 block):
- Propranolol 40-80mg QDS PO or 1-5mg IV slowly
- Esmolol infusion if IV needed and cardiac monitoring available
-
Corticosteroids (reduces T4→T3 conversion, treats relative adrenal insufficiency):
- IV hydrocortisone 100mg QDS or IV dexamethasone 2mg QDS
-
Supportive:
- IV fluids, cooling measures (tepid sponging, fans; AVOID aspirin — displaces T4 from binding proteins)
- Paracetamol for fever
- Treat precipitant (antibiotics if infection)
- Cardiac monitoring, ITU admission
- Cholestyramine 4g QDS: may help by binding thyroid hormone in GI tract
Definitive Treatment
- Once stabilised: plan definitive treatment (radioiodine or thyroidectomy after euthyroid state achieved)
Referral Criteria
- ITU: all suspected thyroid storm
- Endocrinology: urgent consultation
- Surgery: if thyroidectomy needed as definitive treatment
Prognosis
Mortality ~10-30% even with treatment. Prompt recognition and multi-modal treatment improve survival. Poor prognostic factors: older age, coma, jaundice/hepatic failure, cardiovascular collapse, delayed treatment. With modern ICU care and aggressive treatment, outcomes are improving. Survivors require definitive treatment of underlying thyrotoxicosis.
Other Relevant Information
Thyroid Storm Treatment — Order of Administration
| Step | Drug | Mechanism |
|---|---|---|
| 1 | PTU 200mg QDS | Blocks synthesis + T4→T3 |
| 2 (≥1h after ATD) | Lugol iodine | Blocks hormone release |
| 3 | Propranolol 40-80mg QDS | Rate control + T4→T3 block |
| 4 | Hydrocortisone 100mg QDS | T4→T3 block + adrenal support |
| 5 | Supportive | Cooling, fluids, treat precipitant |
Burch-Wartofsky Point Scale (Simplified)
| Parameter | Points |
|---|---|
| Temperature ≥38.5°C | 15-30 |
| CNS effects (agitation-coma) | 10-30 |
| GI/hepatic (diarrhoea-jaundice) | 10-20 |
| Heart rate ≥100 | 5-25 |
| Heart failure (mild-severe) | 5-20 |
| AF present | 10 |
| >45 = thyroid storm likely | — |