21 Sept 2026 · Case #016
Thyroid storm (thyrotoxic crisis)
This page works the case through in full, answer included. If you would rather reason it out yourself: Play this case
Diagnosis
Thyroid storm (thyrotoxic crisis)
First-line treatment
Thionamide (propylthiouracil), beta blocker, and corticosteroids
How the diagnosis is reached
Free T4 and T3 this high do not by themselves make an emergency, since those levels overlap heavily with the thyrotoxicosis that walks into an outpatient clinic. What marks this as storm is the organ failure stacked on top: a temperature of 39.8 °C that the paracetamol given in triage did not touch, agitation with disorientation, atrial fibrillation at 168 with a wide pulse pressure, and bibasal crackles announcing heart failure. Underneath sits months of weight loss despite a large appetite, constant sweating and broken sleep. The diffuse goitre with a bruit, lid lag and a positive TSH receptor antibody name the cause as Graves' disease, untreated since she stopped her thionamide eight months ago. The dental abscess is the precipitant: infection, surgery, trauma, childbirth and iodinated contrast are the classic triggers that tip compensated thyrotoxicosis over. Hypercalcemia reflects thyroid hormone-driven bone resorption, and the raised transaminases and lactate reflect hypermetabolic stress, not separate pathology. The main mimics (sepsis, neuroleptic malignant syndrome, serotonin syndrome and sympathomimetic toxicity) are argued against by the absence of rigidity, clonus and relevant drug exposure, and by fever that persists despite appropriate antibiotics. Treatment is multi-layered and started on clinical suspicion alone: a thionamide (propylthiouracil is preferred in crisis because it also blocks peripheral T4-to-T3 conversion), a beta blocker such as propranolol for adrenergic control, and corticosteroids, which further inhibit conversion and cover the relative adrenal insufficiency of crisis. Iodine, if used, must be given at least an hour after the thionamide, or it will fuel further hormone synthesis. Active cooling and continued treatment of the precipitant run alongside all of it.
Key clinical clues
- Months of weight loss with increased appetite, heat intolerance and a stopped thyroid medication
- A clear precipitant, dental abscess, tipping compensated thyrotoxicosis into crisis
- Hyperpyrexia unresponsive to antipyretics with agitation and altered mental state
- Atrial fibrillation with rapid ventricular response and a wide pulse pressure
- Diffuse goitre with a bruit, lid lag, and positive TSH receptor antibody
The case in full
Presenting complaint
Patient history
A 41-year-old woman is brought in agitated and vomiting. Her partner says she has lost 9 kg in six months despite a large appetite, sweats constantly and sleeps badly. She stopped a tablet for a 'thyroid problem' eight months ago. A dental abscess was drained two days ago.
Vital signs
Vital signs
Paracetamol is given in triage and her temperature is rechecked hourly.
| Parameter | Value | Reference |
|---|---|---|
| Temperature | 39.8 °CRef 36.1–37.5 | 36.1–37.5 |
| Heart rate | 168, irregular bpmRef 60–100 | 60–100 |
| Blood pressure | 162/54 mmHg | – |
| Respiratory rate | 30 /minRef 12–20 | 12–20 |
| Glasgow Coma Scale | 14Ref 15 | 15 |
Physical examination
Physical examination
Her skin is warm and drenched in sweat. There is a fine tremor, lid lag on downward gaze, and a diffusely enlarged smooth thyroid with an audible bruit. She is agitated and intermittently disoriented. The rhythm is irregularly irregular, with bibasal crackles.
Thyroid function tests
Laboratory results
Thyroid function is sent urgently, though treatment is not delayed to await the result.
| Parameter | Value | Reference |
|---|---|---|
| TSH | <0.01 mIU/LRef 0.4–4.0 | 0.4–4.0 |
| Free T4 | 68 pmol/LRef 9–24 | 9–24 |
| Free T3 | 26 pmol/LRef 3.1–6.8 | 3.1–6.8 |
| TSH receptor antibody | Strongly positiveRef Negative | Negative |
Other laboratory results
Laboratory results
Routine bloods are sent.
| Parameter | Value | Reference |
|---|---|---|
| Corrected calcium | 11.4 mg/dLRef 8.5–10.2 | 8.5–10.2 |
| ALT | 94 U/LRef 7–56 | 7–56 |
| Glucose | 182 mg/dLRef 70–110 | 70–110 |
| White blood cells | 13.2 ×10⁹/LRef 4.5–11.0 | 4.5–11.0 |
| Lactate | 3.1 mmol/LRef 0.5–2.2 | 0.5–2.2 |
Clinical course
Clinical course
The ECG confirms atrial fibrillation with a rapid ventricular response. Cultures are sent and antibiotics started for the dental source, but fever and tachycardia persist unchanged over four hours. She takes no antipsychotic or serotonergic drugs, and has no rigidity or clonus.