After reading this note you will be able to recognise, grade and initiate safe emergency management of thyroid storm and myxoedema coma, while knowing which local protocols (Kenya MoH & hospital formulary) must be consulted for drug choices and dosing.
Definition
Thyroid storm – an acute, life‑threatening decompensation of hyperthyroidism characterised by multisystem hypermetabolism, usually precipitated by a stressor in a patient with untreated or inadequately treated Graves’ disease or toxic nodular goitre.
Myxoedema coma – the extreme end of untreated or undertreated hypothyroidism presenting with profound metabolic depression, hypothermia, and altered consciousness, often triggered by infection, drugs or systemic illness.
Anatomy and physiology you need
| Structure | Relevance to crisis |
|---|---|
| Thyroid follicular cells | Synthesize T₃/T₄; excess → storm, deficiency → coma |
| β‑adrenergic receptors | Mediate tachycardia, tremor, heat production in storm |
| Hypothalamic‑pituitary‑thyroid axis | Loss of negative feedback in storm; blunted axis in coma |
| Cardiovascular system | ↑ contractility & heart rate (storm) vs bradycardia, low output (coma) |
| Central nervous system | Hyperexcitability (storm) vs cerebral edema, reduced mental status (coma) |
| Thermoregulatory centre | Hyperthermia (storm) vs hypothermia (coma) |
Causes and risk factors (Kenyan context)
| Condition | How it precipitates storm | How it precipitates coma |
|---|---|---|
| Untreated Graves’ disease | Sudden increase in circulating T₃/T₄ | – |
| Toxic multinodular goitre | Autonomously high hormone output | – |
| Iodine excess (contrast, amiodarone) | Acute surge in hormone synthesis | – |
| Surgery or anaesthesia | Stress → catecholamine surge, hormone release | – |
| Infection (TB, malaria, HIV‑related opportunistic infections) | Cytokines amplify thyroid hormone effects | Fever, metabolic demand precipitates decompensation |
| Drug withdrawal (β‑blockers, antithyroid drugs) | Loss of sympathetic blockade | – |
| Pregnancy/post‑partum | Immune shift, increased thyroid demand | – |
| Severe hypothyroidism (post‑radioiodine, thyroidectomy) | – | Metabolic reserve exhausted |
| Acute illness (pneumonia, sepsis, diarrhoea) | Stress hormones increase hormone conversion | Energy deficit, hypoxia worsen depression |
| Medications (lithium, amiodarone, steroids) | ↑ hormone release or conversion | Inhibit peripheral conversion, precipitate coma |
| Chronic diseases (sickle cell crisis, rheumatic fever) | Heightened inflammatory milieu | Increased catabolism, infection risk |
| Malnutrition & electrolyte disturbances | – | Impaired thermogenesis, cardiac depression |
Pathophysiology
Thyroid storm
Excess T₃/T₄ → ↑ β‑adrenergic stimulation → tachycardia, arrhythmia, ↑ cardiac output → ↑ O₂ demand → tissue hypoxia → lactic acidosis
↑ basal metabolic rate → heat production → hyperthermia → protein catabolism → muscle weakness
Enhanced hepatic gluconeogenesis + insulin resistance → hyperglycaemia → osmotic diuresis → dehydration
Myxoedema coma
Severe T₃/T₄ deficiency → ↓ basal metabolic rate → hypothermia → impaired myocardial contractility → bradycardia, low output → tissue hypoxia
Reduced respiratory drive → hypoventilation → hypercapnia → cerebral vasodilation → altered consciousness
Impaired Na⁺/K⁺ ATPase activity → hyponatraemia, fluid shifts → cerebral oedema
Both crises are amplified by precipitating stressors (infection, drugs, surgery) that further dysregulate the hypothalamic‑pituitary‑thyroid axis and autonomic balance.
The note stops here (part 1 of 3).
Clinical features
| Domain | Key questions / findings | Why it occurs |
|---|---|---|
| Onset | “When did the symptoms start? How rapidly did they progress?” | Thyroid storm and myxoedema coma both evolve quickly; a sudden deterioration after a precipitating event is typical. |
| Temperature | Fever, chills, feeling hot or cold | Hypermetabolism in storm raises core temperature; loss of thermogenesis in coma leads to hypothermia. |
| Cardiac | Palpitations, chest pain, dyspnoea, recent arrhythmia, history of heart disease | Excess thyroid hormone ↑ β‑adrenergic tone → tachycardia, atrial fibrillation, high‑output failure (storm). In myxoedema, bradycardia, low output and pericardial effusion predominate. |
| Neurologic | Confusion, agitation, seizures, coma, tremor, myoclonus, sleepiness | Storm: catecholamine surge, hyperthermia, hypoxia → agitation → seizures. Myxoedema: reduced cerebral metabolism → lethargy → coma; may see “myxedema madness”. |
| Gastro‑intestinal | Nausea, vomiting, diarrhoea, abdominal pain, constipation | Storm stimulates gut motility; myxoedema slows motility → constipation, ileus. |
| Respiratory | Dyspnoea, cough, recent infection, recent intubation | Storm may precipitate pulmonary oedema; myxoedema can cause hypoventilation and CO₂ retention. |
| Skin / mucosa | Sweating, flushing, warm skin vs. dry, cool, coarse hair, facial puffiness, non‑pitting edema | Hyperadrenergic state in storm → diaphoresis; hypothyroid state → myxedema (glycosaminoglycan deposition) and loss of vasomotor tone. |
| Precipitating events | Recent infection (TB, malaria, HIV opportunistic infection), surgery, trauma, iodine load, drug non‑adherence, withdrawal of antithyroid drugs, childbirth | These stressors tip a compensated thyroid disorder into decompensation. |
| Medication history | Antithyroid drugs, levothyroxine, amiodarone, lithium, steroids, β‑blockers, antiretrovirals | Non‑compliance or abrupt changes can precipitate either crisis; amiodarone can cause both hyper‑ and hypothyroidism. |
| Past thyroid disease | Known Graves’ disease, toxic nodular goitre, prior thyroidectomy, long‑standing hypothyroidism | Underlying disease determines which crisis is possible. |
| Other comorbidities | HIV status, TB treatment, sickle‑cell disease, rheumatic heart disease, chronic kidney disease | Co‑existing illnesses increase susceptibility to infection‑related precipitations and alter drug metabolism. |
Examination pearls
- Temperature: >38 °C in storm; <35 °C in myxoedema coma.
- Heart rate: >130 bpm (often irregular) in storm; <60 bpm in coma.
- Blood pressure: Wide pulse pressure or hypertension in storm; hypotension with cold extremities in coma.
- Neurologic: Agitated, hyperreflexic, tremor in storm; sluggish pupils, delayed relaxation of deep tendon reflexes, myxedema facies in coma.
- Skin: Warm, moist, flushed in storm; dry, cool, coarse hair, periorbital and pretibial non‑pitting edema in coma.
- Respiratory: Tachypnoea, possible pulmonary crackles (pulmonary oedema) in storm; shallow, hypoventilatory breathing in coma.
- Abdomen: Tenderness, diarrhoea in storm; distended, tympanic abdomen with reduced bowel sounds in coma.
Differential diagnosis
| Condition | Points toward it | Distinguishing feature |
|---|---|---|
| Sepsis (non‑thyroid) | Fever, tachycardia, source of infection | No prior thyroid disease; thyroid labs normal; cortisol response may be blunted |
| Acute adrenal crisis | Hypotension, hyponatraemia, hyperkalaemia, history of steroids | Low cortisol, high ACTH; rapid response to glucocorticoids |
| Pheochromocytoma crisis | Paroxysmal hypertension, palpitations, diaphoresis | Elevated plasma/urine metanephrines; episodic rather than sustained |
| Malignant hyperthermia (post‑operative) | Recent anaesthesia, muscle rigidity, rapid rise in temperature | Triggered by volatile agents; normal thyroid function |
| Drug‑induced delirium (e.g., anticholinergics) | Recent new medication, dry mouth, urinary retention | Anticholinergic signs, normal thyroid labs |
| Acute heart failure (decompensated) | Dyspnoea, pulmonary oedema, peripheral edema | BNP markedly raised; cardiac imaging shows systolic dysfunction |
| CNS infection (meningitis, encephalitis) | Neck stiffness, photophobia, focal neuro signs | CSF pleocytosis, pathogen identified |
Investigations
| Test | What it answers | Interpretation |
|---|---|---|
| Free T4 (or total T4) | Current thyroid hormone level | Markedly ↑ in storm; markedly ↓ in myxoedema coma |
| TSH | Pituitary response | Suppressed in storm; markedly ↑ in myxoedema coma |
| Thyroid antibodies (TRAb, TPO) | Underlying aetiology | Positive TRAb supports Graves’ (storm); TPO may be positive in autoimmune hypothyroidism |
| CBC & differential | Infection, anemia, leukocytosis | Neutrophilia suggests bacterial precipitant; eosinophilia may hint at parasitic infection |
| Blood cultures | Sepsis source | Positive cultures support infectious trigger |
| Electrolytes, renal & liver panel | Organ dysfunction, hyponatraemia (common in coma) | Hyponatraemia, elevated transaminases common in myxoedema coma |
| Arterial blood gas (ABG) | Acid‑base status, CO₂ retention | Respiratory acidosis in myxoedema coma; metabolic acidosis may accompany storm |
| ECG | Arrhythmias, QT changes | AF with rapid ventricular response in storm; bradyarrhythmias, low voltage in coma |
| Chest X‑ray | Pulmonary oedema, infection | Pulmonary infiltrates in storm; pleural effusion possible in coma |
| Echocardiography | Cardiac function, pericardial effusion | High‑output failure in storm; low‑output, tamponade in severe myxoedema |
| Serum cortisol (random) | Exclude adrenal insufficiency | Low cortisol supports adrenal crisis as co‑trigger |
| Urine output & fluid balance | Renal perfusion, volume status | Oliguria in shock; polyuria may occur with hyperglycaemia in storm |
Diagnosis and severity
Thyroid storm – clinical diagnosis based on a scoring system (e.g., Burch–Wartofsky). Key elements: temperature >38 °C, CNS agitation, gastrointestinal upset, cardiovascular dysfunction (tachycardia >130 bpm, atrial fibrillation, heart failure), precipitating event. A score ≥45 denotes storm; 25–44 suggests impending storm; <25 is unlikely.
Myxoedema coma – clinical diagnosis supported by severe hypothyroid labs (free T4 markedly low, TSH >30 µIU/mL) plus at least one of: hypothermia <35 °C, altered mental status (GCS ≤8), bradycardia <60 bpm, hypotension, respiratory failure, or precipitating illness. Severity is graded by the number of organ systems involved:
- Mild – one system (e.g., hypothermia only)
- Moderate – two–three systems (e.g., hypothermia + bradycardia + hypotension)
- Severe – four or more systems, especially if mechanical ventilation required.
Prompt recognition of the pattern (hyper‑ vs. hypo‑metabolic) and the scoring thresholds guides urgency of therapy and level of monitoring (high‑dependency unit vs. ICU).
Management
1. Immediate stabilisation
| Goal | Immediate actions | Rationale |
|---|---|---|
| Airway‑breathing‑circulation | Position semi‑upright, give high‑flow O₂, secure airway if GCS < 8 or severe respiratory failure, start IV crystalloid bolus (isotonic) | Prevent hypoxia, improve tissue perfusion; thyroid hormones increase metabolic demand and can precipitate shock |
| Temperature control | Cool the patient with tepid sponging, fan, antipyretics (paracetamol) for TS; passive re‑warming for MC | Hyperthermia worsens tachyarrhythmia in TS; hypothermia worsens bradycardia in MC |
| Cardiovascular support | Give IV beta‑blocker (e.g., propranolol) after fluid resuscitation; consider short‑acting vasopressor (e.g., norepinephrine) if hypotensive despite fluids | Propranolol blocks peripheral conversion of T4→T3 and controls adrenergic surge; vasopressor maintains MAP while thyroid blockade takes effect |
| Glucose & electrolytes | Check bedside glucose; give dextrose if < 70 mg/dL; correct hypokalemia, hyponatraemia | Both crises can cause metabolic derangements that precipitate arrhythmias and seizures |
2. Definitive treatment
| Thyroid storm (TS) | Myxoedema coma (MC) |
|---|---|
| Block hormone synthesis – give a thionamide (e.g., propylthiouracil or methimazole) as soon as possible | Replace hormone – give IV levothyroxine (large loading dose) followed by daily maintenance |
| Block peripheral conversion – propranolol (also reduces tachycardia) | Support adrenal axis – give IV hydrocortisone (stress dose) before thyroid hormone to avoid precipitating adrenal insufficiency |
| Inhibit hormone release – iodine solution (e.g., Lugol’s) after thionamide, 1 hour later, for 10–14 h | Correct precipitating factors – treat infection (malaria, TB, HIV‑related sepsis), stop offending drugs (e.g., amiodarone), optimise fluid/electrolytes |
| Treat precipitant – broad‑spectrum antibiotics if infection suspected, stop antithyroid drugs if allergic, manage heart failure, correct electrolyte disturbances | Supportive care – ventilatory support if CO₂ retention, careful re‑warming (avoid rapid rise > 1 °C/h), treat hyponatraemia slowly |
3. Monitoring & safety
- Vital signs: continuous ECG, pulse oximetry, temperature, urine output.
- Cardiac: watch for atrial fibrillation, ventricular tachyarrhythmia; beta‑blocker dose titrated to heart rate < 100 bpm.
- Laboratory: 6‑hourly TFTs (free T4, T3), electrolytes, liver function, coagulation profile.
- Neurological: GCS hourly; watch for seizures (give benzodiazepine if needed).
- Drug safety: avoid iodine before thionamide (risk of worsening synthesis); avoid high‑dose beta‑blocker in severe asthma or decompensated heart failure; monitor for agranulocytosis with thionamides (CBC daily).
4. Follow‑up
- Transition to oral thionamide once stable, continue beta‑blocker until euthyroid.
- In MC, once core temperature > 35 °C and hemodynamics stable, taper hydrocortisone and switch to oral levothyroxine.
- Arrange endocrinology review, patient education on medication adherence, and screening for precipitating chronic illnesses (HIV, TB, autoimmune disease).
Complications and prognosis
| Condition | Early complications | Late sequelae | Prognostic factors |
|---|---|---|---|
| Thyroid storm | Cardiac failure, atrial fibrillation, ventricular tachycardia, pulmonary edema, hepatic dysfunction, DIC, sepsis | Persistent cardiomyopathy, neurocognitive deficits after prolonged hypoxia | Prompt recognition, control of temperature, early thionamide + beta‑blocker, absence of multi‑organ failure |
| Myxoedema coma | Respiratory failure, severe bradyarrhythmia, hypotension, hypoglycaemia, hyponatraemia, myxedema‑related skin breakdown | Prolonged ventilatory dependence, neuro‑cognitive impairment, recurrent hypothyroid crises if precipitant not addressed | Age > 60 y, delayed re‑warming, co‑existent infection (malaria, TB, HIV), severe electrolyte derangement |
Overall mortality remains high (≈ 10–30 %) but falls dramatically with early, protocol‑driven management.
High‑yield exam points
- Look‑alike conditions:
- TS vs. sepsis with fever and tachycardia – presence of overt hyperthyroid signs (exophthalmos, goitre, tremor) points to TS.
- MC vs. opioid overdose – MC has hypothermia, bradycardia, delayed reflexes, and markedly abnormal TFTs.
- Commonest wrong first step: Giving antipyretics alone without beta‑blockade in TS; the adrenergic surge persists.
- Examiner bedside questions:
- “What feature distinguishes thyroid storm from uncomplicated thyrotoxicosis?” – answer: acute decompensation with fever > 38 °C, CNS agitation, and cardiovascular collapse.
- “Why must iodine be given after a thionamide?” – because iodine can be used by the thyroid to make more hormone if synthesis is not blocked.
- “Explain the rationale for giving glucocorticoids in myxoedema coma.” – they provide stress‑dose adrenal support and reduce peripheral conversion of T4 to T3.
Clinical case
Case: A 28‑year‑old Kenyan woman, 3 weeks postpartum, presents with sudden agitation, profuse sweating, temperature 39.5 °C, heart rate 150 bpm, atrial fibrillation, and a palpable diffuse goitre. TFTs: free T4 markedly elevated, suppressed TSH.
Questions
- What is the most urgent first therapeutic action?
Answer: Initiate IV propranolol to control the adrenergic storm and reduce peripheral T4→T3 conversion.
- Which drug should be added after the beta‑blocker and why?
Answer: A thionamide (propylthiouracil) to block new hormone synthesis; it also further reduces T4→T3 conversion.
- If the patient develops a fever of 41 °C despite cooling measures, what adjunctive therapy is indicated?
Answer: Administer intravenous paracetamol and intensify external cooling; consider adding a short‑acting vasodilator (e.g., nitroglycerin) if hypertension persists, while ensuring adequate fluid resuscitation.
Practice questions
Question 1
A 65‑year‑old man with known hypothyroidism is found unconscious, hypothermic (32 °C), bradycardic (40 bpm), and hyponatraemic. Which immediate intervention is most appropriate?
A. High‑dose propranolol
B. Rapid active re‑warming with hot blankets
C. Intravenous levothyroxine loading dose
D. Immediate cardioversion
Answer: C. Intravenous levothyroxine loading dose
Explanation: Myxoedema coma requires rapid hormone replacement; active re‑warming is done slowly to avoid vasodilation‑induced hypotension.
Question 2
A patient with thyroid storm is given iodine before a thionamide. What is the most likely consequence?
A. Immediate reduction in heart rate
B. Worsening of thyrotoxicosis
C. Development of agranulocytosis
D. No effect on the crisis
Answer: B. Worsening of thyrotoxicosis
Explanation: Iodine provides substrate for hormone synthesis; without a thionamide block, hormone production can increase.
Question 3
In a febrile patient with atrial fibrillation, how can you differentiate thyroid storm from septic shock?
A. Measure serum cortisol
B. Look for goitre and ophthalmopathy
C. Perform a lumbar puncture
D. Check serum lactate
Answer: B. Look for goitre and ophthalmopathy
Explanation: Physical signs of thyrotoxicosis point toward thyroid storm, whereas sepsis lacks these endocrine features.
Question 4
A 40‑year‑old woman with newly diagnosed Graves’ disease presents with fever, agitation, and a heart rate of 140 bpm. Which drug class should be avoided as the first line?
A. Thionamides
B. Beta‑blockers
C. Calcium channel blockers
D. Glucocorticoids
Answer: C. Calcium channel blockers
Explanation: They do not reduce peripheral conversion of T4 to T3 and are less effective for controlling the adrenergic surge.
Question 5
During management of myxoedema coma, a patient develops severe hyponatraemia. The safest correction strategy is:
A. Rapid infusion of hypertonic saline
B. Slow correction with isotonic saline and monitoring
C. No fluid therapy, give diuretics
D. Immediate dialysis
Answer: B. Slow correction with isotonic saline and monitoring
Explanation: Rapid shifts risk central pontine myelinolysis; gradual correction aligns with guidelines for hyponatraemia in MC.
Drafted with AI assistance from standard references and reviewed for structure. Check details against your lecture notes and the Kenya MoH guideline.