🌡️ Thyroid Storm — Overview
Thyroid storm (thyrotoxic crisis) is a rare but life-threatening exacerbation of hyperthyroidism characterised by extreme hypermetabolism, cardiovascular decompensation, and neurological dysfunction.
Mortality: 10–30% even with treatment. Thyroid storm is a medical emergency requiring immediate ICU admission and multi-drug therapy.
Precipitating Factors
Common Precipitants
- Infection / sepsis (most common)
- Surgery (especially thyroid surgery)
- Radioiodine therapy
- Abrupt cessation of antithyroid drugs
- Iodine contrast administration (CT scan dye)
- Trauma
- Acute illness (MI, DKA, PE)
- Pregnancy
Clinical Features
- High fever (>38.5°C, often >40°C)
- Tachycardia (>140 bpm) or AF
- Agitation, confusion, psychosis, coma
- Profuse sweating
- Nausea, vomiting, diarrhoea
- Heart failure
- Jaundice (hepatic involvement)
Underlying Cause
- Graves' disease — most common underlying cause (80%)
- Toxic multinodular goitre
- Toxic adenoma
- Iodine-induced hyperthyroidism (Jod-Basedow effect — amiodarone, contrast dye)
Amiodarone and thyroid storm: Amiodarone contains 37% iodine by weight — each tablet contains ~75 mg iodine (recommended daily iodine intake: 150 mcg). Can cause amiodarone-induced thyrotoxicosis (AIT) which can precipitate thyroid storm. Carbimazole/PTU for Type 1 AIT; prednisolone for Type 2.
📊 Burch-Wartofsky Score (BWS)
The Burch-Wartofsky Score quantifies the likelihood of thyroid storm based on clinical features. Scoring is additive.
| Parameter | Score |
|---|
| Thermoregulatory Dysfunction |
| Temperature 37.2–37.7°C | 5 |
| Temperature 37.8–38.2°C | 10 |
| Temperature 38.3–38.8°C | 15 |
| Temperature 38.9–39.4°C | 20 |
| Temperature 39.5–39.9°C | 25 |
| Temperature ≥40°C | 30 |
| Cardiovascular |
| HR 100–109 bpm | 5 |
| HR 110–119 bpm | 10 |
| HR 120–129 bpm | 15 |
| HR 130–139 bpm | 20 |
| HR ≥140 bpm | 25 |
| AF present | 10 |
| Heart failure: mild (oedema only) | 5 |
| Heart failure: moderate (bibasal crepts) | 10 |
| Heart failure: severe (pulmonary oedema) | 15 |
| CNS Effects |
| Absent | 0 |
| Mild (agitation) | 10 |
| Moderate (delirium, psychosis) | 20 |
| Severe (seizures, coma) | 30 |
| GI Dysfunction |
| Absent | 0 |
| Moderate (diarrhoea, vomiting) | 10 |
| Severe (jaundice) | 20 |
| Precipitating Event |
| Absent | 0 |
| Present | 10 |
| BWS Total Score | Interpretation |
|---|
| ≥45 | Thyroid storm — treat immediately |
| 25–44 | Impending thyroid storm — treat urgently |
| <25 | Unlikely thyroid storm |
💊 Thyroid Storm Treatment Protocol
Treatment order is CRITICAL — must follow sequence below. Multiple drugs work at different steps of thyroid hormone synthesis and release.
Step 1: Antithyroid Drugs (Block NEW Hormone Synthesis)
Propylthiouracil (PTU) is PREFERRED over carbimazole in thyroid storm because PTU also blocks peripheral conversion of T4 → T3 (carbimazole does not).
PTU: 600–1000 mg loading dose orally/NG, then 200–250 mg every 4 hours
OR Carbimazole: 60–80 mg loading, then 15–20 mg QDS if PTU unavailable
Step 2: Iodide (Block Thyroid Hormone RELEASE) — 1 Hour AFTER PTU
CRITICAL: Iodide must be given AT LEAST 1 hour AFTER PTU/carbimazole.
Why: Iodide provides substrate for hormone synthesis. If given before antithyroid drugs, it WORSENS thyroid storm (Wolff-Chaikoff effect is delayed).
Lugol's iodine (5% iodine + 10% potassium iodide): 0.5–1 mL orally QDS
OR Saturated solution of potassium iodide (SSKI): 5 drops TDS
OR Sodium iodide IV if oral route not possible
Step 3: Beta-Blocker (Control Adrenergic/Cardiovascular Effects)
- Propranolol 40–80 mg orally every 4–6 hours (also blocks T4→T3 peripheral conversion)
- OR IV esmolol infusion (titratable, short-acting — preferred in haemodynamically unstable)
- Caution: heart failure (may need careful dosing or avoid)
Step 4: Hydrocortisone (Reduce Peripheral T4→T3 Conversion; Treat Relative Adrenal Insufficiency)
- Hydrocortisone 100 mg IV every 8 hours
- Thyroid storm depletes adrenal reserves; cortisol also blocks peripheral T4→T3 conversion
Step 5: Treat Precipitating Cause
- Antibiotics if infection suspected
- Anticoagulation if AF (high stroke risk)
- Cooling for hyperthermia: paracetamol (NOT aspirin — displaces T4 from protein binding, worsening storm); cooling blankets, ice packs
Step 6: Supportive ICU Care
- IV fluids (replace losses from sweating, diarrhoea, vomiting)
- Continuous cardiac monitoring
- Nutritional support
- Benzodiazepines for agitation
Do NOT give aspirin for fever in thyroid storm — aspirin displaces thyroid hormones (T4) from binding proteins → increases free T4 → WORSENS storm. Use paracetamol only.
🩺 Nursing Care Priorities
Monitoring
- Continuous cardiac monitoring (HR, rhythm — AF very common)
- Core temperature every 1–2 hours; active cooling if >39°C
- BP and SpO₂ hourly
- Fluid balance (strict input/output) — significant fluid losses from hyperthermia
- Neurological assessment (GCS, agitation level) every 2 hours
- Blood glucose monitoring — thyroid storm can cause hyperglycaemia
Temperature Management
- Cooling blankets, cool wet towels, ice packs to axillae/groin
- Paracetamol 1g IV/oral QDS for antipyresis
- Avoid aspirin and NSAIDs
- Cool IV fluids if appropriate
- Air conditioning to lowest comfortable setting
Medication Administration Sequence
Iodide timing is the most critical nursing responsibility in thyroid storm.
Document exact time PTU/carbimazole was administered → ensure iodide is NOT given until at least 60 minutes later. Label iodide with "Give after [time]" sticker. Incorrect sequence (iodide before antithyroid drug) worsens the crisis.
Education and Prevention
- Educate hyperthyroid patients about compliance with antithyroid medications
- Identify and address triggers: missed medications, infection management
- Pre-contrast CT risk: inform team of known hyperthyroidism before iodine contrast administration
- Pre-operative optimisation before any thyroid surgery