Thyroid storm vs Pheochromocytoma or sympathomimetic toxidrome
How to tell Thyroid storm and Pheochromocytoma or sympathomimetic toxidrome apart when a board question makes them look alike.
Thyroid storm is fever plus decompensated thyrotoxicosis with abnormal thyroid labs; pheo/sympathomimetic is catecholamine excess with metanephrines or drug exposure.
Side by side
Life-threatening decompensated thyrotoxicosis with high fever, severe tachycardia or atrial fibrillation, agitation, delirium, vomiting, diarrhea, and heart failure risk.
Catecholamine excess causes episodic headache, sweating, palpitations, hypertension, tremor, and anxiety; sympathomimetics add drug exposure, mydriasis, hyperthermia, and agitation.
Excess thyroid hormone creates systemic hypermetabolism, often triggered by infection, surgery, trauma, delivery, or withdrawal of antithyroid therapy.
Adrenal medullary tumor or stimulant exposure increases adrenergic signaling without primary thyroid hormone overproduction.
Suppressed TSH with high free T4/T3 and history of Graves or untreated hyperthyroidism supports thyroid storm.
Elevated plasma or urine metanephrines supports pheochromocytoma; stimulant screen or exposure supports sympathomimetic toxidrome.
The trap
Both can cause tachycardia, sweating, tremor, and hypertension, so thyroid labs, fever severity, and exposure history are decisive.
The repair move
For adrenergic-looking endocrine emergencies, decide whether thyroid hormone is driving systemic decompensation or catecholamines are.
Try a free question
CoreA patient with untreated Graves disease develops pneumonia, hyperpyrexia, delirium, vomiting, atrial fibrillation, low TSH, and markedly elevated free T4. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Thyroid storm. Severe systemic decompensation from thyrotoxicosis after a trigger points to thyroid storm.
Why the other choices are tempting
- B. Pheochromocytoma causes catecholamine episodes and metanephrine elevation, not primary thyrotoxicosis.
- C. Sympathomimetic toxidrome needs stimulant exposure and does not cause high thyroid hormone levels.
- D. Serotonin syndrome has serotonergic exposure, clonus, and hyperreflexia.
- E. Neuroleptic malignant syndrome follows dopamine blockade and causes lead-pipe rigidity.
Flashcards
Tap a card to flip it.
What presentation points to thyroid storm?
Severe thyrotoxicosis with fever, delirium, tachyarrhythmia, GI symptoms, and heart failure risk points to thyroid storm.
What classic triad points to pheochromocytoma?
Episodic headache, sweating, and palpitations with hypertension points to pheochromocytoma.
Quick answers
What is the fastest way to tell Thyroid storm from Pheochromocytoma or sympathomimetic toxidrome?
Thyroid storm is fever plus decompensated thyrotoxicosis with abnormal thyroid labs; pheo/sympathomimetic is catecholamine excess with metanephrines or drug exposure.
What is the key clue for Thyroid storm?
Life-threatening decompensated thyrotoxicosis with high fever, severe tachycardia or atrial fibrillation, agitation, delirium, vomiting, diarrhea, and heart failure risk.
What is the key clue for Pheochromocytoma or sympathomimetic toxidrome?
Catecholamine excess causes episodic headache, sweating, palpitations, hypertension, tremor, and anxiety; sympathomimetics add drug exposure, mydriasis, hyperthermia, and agitation.
What is the common trap with Thyroid storm vs Pheochromocytoma or sympathomimetic toxidrome?
Both can cause tachycardia, sweating, tremor, and hypertension, so thyroid labs, fever severity, and exposure history are decisive.