Pheochromocytoma vs Hyperthyroidism
How to tell Pheochromocytoma and Hyperthyroidism apart when a board question makes them look alike.
Step 2 CK pairs are in open beta while clinical review finishes. Spot an issue? Tell us.
Episodic adrenergic spells with severe BP surges favor pheochromocytoma, while sustained thyrotoxic symptoms with suppressed TSH favor hyperthyroidism.
Side by side
Paroxysmal hypertension spells with episodic headache, diaphoresis, and palpitations suggest catecholamine-secreting tumor.
Persistent tachycardia, heat intolerance, weight loss, tremor, and diffuse goiter suggest thyrotoxicosis.
Pheochromocytoma secretes excess catecholamines from chromaffin tissue, driving episodic sympathetic surges.
Hyperthyroidism increases metabolic and beta-adrenergic signaling through excess circulating thyroid hormone.
Plasma free metanephrines above the assay upper limit, often over 2 to 3 times normal, strongly support pheochromocytoma and are followed by CT or MRI localization after biochemical confirmation.
Primary hyperthyroidism shows suppressed TSH, typically below 0.01 mIU/L, with elevated free T4 or T3; thyrotropin receptor antibodies or diffuse uptake on radioiodine scan support Graves disease.
The trap
Starting a beta blocker alone in undiagnosed pheochromocytoma can worsen hypertension through unopposed alpha stimulation. Spell-like symptoms plus very high episodic blood pressure should trigger metanephrine testing before empiric thyroid-directed treatment.
The repair move
Next best step: confirm biochemical pheochromocytoma with plasma or 24-hour urine metanephrines, then start alpha blockade such as phenoxybenzamine 10 mg twice daily and titrate over 7 to 14 days before adding beta blockade if needed for tachycardia. After adequate alpha blockade and volume repletion, proceed to adrenalectomy.
Try a free question
CoreA 33-year-old man has 6 months of recurrent palpitations, headache, and sweating episodes. During one episode his BP is 210/116 mm Hg and HR 118/min; between episodes BP is 132/80 mm Hg. TSH is 1.4 mIU/L. What is the most likely diagnosis?
Show answer and explanation
Answer: A. Pheochromocytoma. Paroxysmal adrenergic spells with dramatic episodic hypertension and normal TSH are classic for pheochromocytoma.
Why the other choices are tempting
- B. Hyperthyroidism usually causes sustained symptoms with suppressed TSH rather than isolated hypertensive spells.
- C. Panic disorder does not typically cause repeated severe hypertensive spikes above 200 systolic with biochemical evidence of catecholamine excess.
- D. Carcinoid syndrome usually presents with flushing and diarrhea rather than episodic severe hypertension.
- E. Primary hyperaldosteronism causes persistent hypertension and hypokalemia, not episodic sympathetic crises.
Flashcards
Tap a card to flip it.
Which symptom pattern should immediately raise concern for pheochromocytoma?
Brief recurrent attacks of headache, diaphoresis, palpitations, and severe hypertension are classic for pheochromocytoma.
Which laboratory signature identifies primary hyperthyroidism?
Suppressed TSH with elevated free T4 or T3 identifies primary hyperthyroidism.
Quick answers
What is the fastest way to tell Pheochromocytoma from Hyperthyroidism?
Episodic adrenergic spells with severe BP surges favor pheochromocytoma, while sustained thyrotoxic symptoms with suppressed TSH favor hyperthyroidism.
What is the key clue for Pheochromocytoma?
Paroxysmal hypertension spells with episodic headache, diaphoresis, and palpitations suggest catecholamine-secreting tumor.
What is the key clue for Hyperthyroidism?
Persistent tachycardia, heat intolerance, weight loss, tremor, and diffuse goiter suggest thyrotoxicosis.
What is the common trap with Pheochromocytoma vs Hyperthyroidism?
Starting a beta blocker alone in undiagnosed pheochromocytoma can worsen hypertension through unopposed alpha stimulation. Spell-like symptoms plus very high episodic blood pressure should trigger metanephrine testing before empiric thyroid-directed treatment.