Thyroid Storm Clinical Overview
I. The "On-Call" Snapshot
Clinical Significance in Malaysia: This is a high-mortality endocrine emergency you will encounter in the ED or medical wards. It is frequently missed because it presents as undifferentiated shock or sepsis, and a delayed diagnosis is often fatal.
High-Yield Definition: A life-threatening manifestation of thyrotoxicosis characterized by decompensation of one or more organ systems. The diagnosis is clinical, not biochemical. (Source: UpToDate, 2024).
Clinical One-Liner: Think of it as a multisystem crash from a massive, unopposed thyroid hormone dump, leading to a severe hyperadrenergic state.
II. Etiology & Risk Factors
Etiology: Thyroid storm occurs in patients with pre-existing, often undiagnosed or poorly controlled, thyrotoxicosis (most commonly Graves' disease) who are exposed to a precipitating event.
Common Precipitants:
Infection: The most common trigger (e.g., pneumonia, urosepsis).
Surgery: Especially thyroid surgery in an unprepared patient.
Trauma.
Sudden withdrawal of anti-thyroid drugs (ATDs).
Iodine Load: E.g., from iodinated contrast media.
Parturition (Childbirth).
Diabetic Ketoacidosis (DKA).
III. Quick Pathophysiology
The core mechanism is not just high levels of thyroid hormone, but a rapid increase in hormone levels combined with an exaggerated systemic response. This leads to a massive catecholamine surge, causing widespread adrenergic overstimulation. This explains the cardinal features: profound hyperthermia (from uncoupled oxidative phosphorylation), tachycardia, and CNS dysfunction.
IV. Classification
Thyroid storm is a clinical diagnosis. The Burch-Wartofsky Point Scale (BWPS) is the most widely used tool to aid diagnosis. It is not a confirmatory test but helps quantify the likelihood.
Score ≥ 45: Highly suggestive of thyroid storm.
Score 25-44: Suggestive; impending storm.
Score < 25: Storm unlikely.
V. Clinical Assessment
🚩 Red Flags & Immediate Actions
GCS < 15 / Seizures: Action: Secure airway (ABCDE approach), check capillary blood glucose immediately. Reason: Indicates severe CNS dysfunction.
Hypotension: Action: Secure two large-bore IV cannulas, start fluid resuscitation (IV Normal Saline 0.9%), call for senior help. Reason: Signifies impending cardiovascular collapse/shock.
Temperature > 40°C: Action: Initiate active cooling (e.g., cooling blankets, ice packs to axillae/groin), give IV Paracetamol. Reason: Severe hyperthermia can cause rhabdomyolysis and irreversible brain damage.
Atrial Fibrillation with RVR > 120 bpm: Action: Get an urgent 12-lead ECG, start beta-blockade (e.g., Propranolol) once stable. Reason: Risk of high-output cardiac failure.
History
Key Diagnostic Clues: The classic triad is Fever + Tachycardia + Altered Mental Status in a patient with signs or history of hyperthyroidism.
Symptom Breakdown:
Common (>50%): Fever, profuse sweating, palpitations, severe agitation, anxiety, delirium.
Less Common (10-50%): Diarrhoea, vomiting, abdominal pain, jaundice (due to hepatic congestion/dysfunction).
Rare (<10%): Psychosis, seizures, coma.
Pertinent Negatives: Absence of a goitre or known thyroid history makes it less likely but does not exclude it. A normal temperature is a strong negative predictor.
Physical Examination (OSCE Approach)
General Inspection: Patient looks toxic, agitated, tremulous, diaphoretic, with a frightened "thyroid stare" (lid lag/retraction).
Vitals:
Tachycardia: Sinus tachycardia or fast atrial fibrillation, often out of proportion to the fever.
Fever: Usually high-grade (>38.5°C).
Hypotension: With a wide pulse pressure (late and ominous sign).
Tachypnoea.
Disease-Specific Examination:
Neck: Look for a goitre (diffuse/nodular), listen for a thyroid bruit.
Eyes: Check for exophthalmos, lid lag, lid retraction.
Hands: Fine tremor, palmar erythema, warm and sweaty palms.
Neurology: Brisk reflexes (hyperreflexia), confusion, agitation.
Cardiovascular: Tachyarrhythmias, flow murmurs, signs of high-output cardiac failure (e.g., pulmonary oedema).
Clinical Pearl: When you see a patient with fever, tachycardia, and delirium, sepsis is your first thought. But if the peripheries are warm and bounding despite hypotension, put thyroid storm high on your list of differentials.
VI. Diagnostic Workflow
Differential Diagnosis
Sepsis / Septic Shock
Points For: Fever, tachycardia, hypotension, altered mental state.
Points Against: Absence of a clear infective source, warm peripheries despite shock.
How to Differentiate: A positive septic workup (cultures, imaging) and response to antibiotics. TFTs are key.
Neuroleptic Malignant Syndrome (NMS) / Serotonin Syndrome
Points For: Fever, altered mental state, autonomic instability.
Points Against: Presence of lead-pipe rigidity and hyporeflexia (NMS) or clonus (Serotonin Syndrome) instead of hyperreflexia.
How to Differentiate: A clear drug history (antipsychotics for NMS, SSRIs/MAOIs for SS).
Pheochromocytoma Crisis
Points For: Paroxysmal hypertension, tachycardia, headache, sweating.
Points Against: Usually presents with severe hypertension, not hypotension.
How to Differentiate: Urinary/plasma metanephrines.
Investigations Plan
Bedside / Initial (First 15 Mins):
ECG: Look for sinus tachycardia, AF, other tachyarrhythmias.
Capillary Blood Glucose: Rule out hypoglycemia as a cause for altered mental state.
First-Line Labs & Imaging:
Thyroid Function Tests (TFTs): Stat request. Expect suppressed TSH (<0.01 mIU/L) with markedly elevated Free T4 and/or Free T3.
Full Blood Count: Leucocytosis can occur even without infection.
Renal Profile & Electrolytes.
Liver Function Test: Often shows a cholestatic or hepatocellular pattern.
Septic Workup: Blood C&S, Urine FEME & C&S, CXR to rule out infection.
Creatine Kinase (CK): May be elevated.
Confirmatory / Gold Standard:
The diagnosis is CLINICAL. Do not wait for TFT results to initiate treatment if your suspicion is high (BWPS ≥ 45). The TFTs confirm the underlying thyrotoxicosis but not the storm itself.
VII. Staging & Severity Assessment
Severity is assessed clinically based on the degree of organ dysfunction (e.g., GCS, haemodynamic stability, degree of hyperthermia) and the Burch-Wartofsky Point Scale. Management intensity is guided by this clinical assessment, not just the TFT numbers.
VIII. Management Plan
A. Principle of Management
A multi-pronged attack:
Block peripheral adrenergic effects.
Block new thyroid hormone synthesis.
Block the release of stored thyroid hormone.
Block peripheral conversion of T4 to T3.
Identify and treat the underlying precipitant.
B. Immediate Stabilisation (The ABCDE Plan)
A/B: High-flow oxygen. Low threshold for intubation if GCS is low or patient is tiring.
C: Two large-bore IV cannulas. Aggressive fluid resuscitation. Consider vasopressors (e.g., noradrenaline) for persistent hypotension after fluid challenge.
D: Continuous cardiac monitoring. Treat arrhythmias.
E: Active cooling measures. IV Paracetamol 1g QDS. Avoid aspirin as it can displace thyroid hormone from binding proteins.
C. Definitive Treatment (The Ward Round Plan)
Must be started immediately upon suspicion.
Beta-Blockade (Blocks peripheral effects):
Propranolol: 40-80 mg PO/NG every 4-6 hours. If unable to take orally, IV Propranolol 1 mg given slowly over 10 minutes, can be repeated.
Thionamide (Blocks new hormone synthesis):
Propylthiouracil (PTU): Preferred agent as it also blocks peripheral T4 to T3 conversion.
Dose: 600-1000 mg PO/NG STAT (loading dose), then 200-250 mg every 4-6 hours.
Iodine Solution (Blocks hormone release - Wolff-Chaikoff effect):
Timing is CRITICAL: Give AT LEAST ONE HOUR AFTER the first dose of PTU. Giving iodine first provides more substrate for new hormone synthesis.
Preparation: Lugol's Iodine (8 drops every 6 hours) or Saturated Solution of Potassium Iodide (SSKI) (5 drops every 6 hours) via NG tube.
Glucocorticoids (Blocks T4-to-T3 conversion & treats potential adrenal insufficiency):
IV Hydrocortisone: 300 mg STAT (loading dose), then 100 mg every 8 hours.
Treat Precipitant:
Start empirical broad-spectrum antibiotics if sepsis is suspected.
D. Long-Term & Discharge Plan
Once the acute storm resolves (usually within 24-72 hours), taper steroids and iodine solution. Continue PTU and Propranolol. The patient will need definitive management for the underlying hyperthyroidism (e.g., radioiodine ablation or surgery) planned as an outpatient with the endocrine team.
IX. Complications
Immediate: High-output cardiac failure, fatal arrhythmias, seizures, coma, death.
Short-Term: Agranulocytosis (from PTU), hepatotoxicity.
Long-Term: Complications related to the underlying cause of hyperthyroidism.
X. Prognosis
Even with modern ICU care, mortality remains significant at 10-30%. The main predictors of poor prognosis are advanced age, presence of CNS symptoms at presentation, and the need for mechanical ventilation.
XI. How to Present to Your Senior
Use the SBAR format. Be clear and concise.
(Situation): "Dr, I am calling about Patient [Name], in [Bed Number], Ward [X]. I am very concerned they are in thyroid storm."
(Background): "This is a [Age]-year-old [lady/man] with a known history of [e.g., Graves' disease on treatment/defaulted treatment] who was admitted for [e.g., pneumonia]."
(Assessment): "Currently, the patient is agitated and confused with a GCS of [e.g., 13]. Vitals are: BP [x/y], HR [rate] in AF, RR [rate], Temp [temp]. The Burch-Wartofsky score is [e.g., 50]. The main issues are hyperthermia, tachyarrhythmia, and delirium."
(Recommendation): "I have started ABCDE management with oxygen and IV fluids. I think we need to start treatment for thyroid storm now. I would like to prescribe IV Hydrocortisone, Propranolol, and oral PTU. I have already sent off stat TFTs and a full septic workup. I need you to come and review urgently."
XII. Summary & Further Reading
Top 3 Takeaways:
Thyroid storm is a clinical diagnosis; treat based on suspicion and do not wait for TFT results.
Management is multi-faceted: Block effects (Propranolol), synthesis (PTU), release (Iodine), and conversion (Steroids, PTU).
Crucial Safety Step: Always give the thionamide (PTU) at least one hour BEFORE the iodine solution.
Key Resources:
Malaysian Endocrine & Metabolic Society (MEMS) guidelines (often integrated into general medical protocols).
UpToDate: "Thyroid storm".
Amboss: "Thyrotoxic crisis".
