## Distinguishing Pheochromocytoma from Essential Hypertension ### Key Discriminating Feature **Key Point:** The hallmark of pheochromocytoma is **paroxysmal (episodic) hypertension** with symptom-free intervals between attacks, whereas essential hypertension is sustained and chronic. ### Comparative Table | Feature | Pheochromocytoma | Essential Hypertension | |---------|------------------|------------------------| | **Blood Pressure Pattern** | Paroxysmal (episodic spikes) | Sustained elevation | | **Symptom Timing** | Acute episodes: headache, sweating, palpitations | Chronic, often asymptomatic | | **Between Episodes** | Normal or near-normal BP | Persistently elevated | | **Catecholamine Surge** | Massive, episodic release | Normal levels | | **Plasma Free Metanephrines** | Markedly elevated (>4× upper limit) | Normal | ### Clinical Pearl **Clinical Pearl:** The classic triad of pheochromocytoma is **sudden-onset headache + profuse sweating + palpitations**, occurring in discrete episodes lasting minutes to hours. This episodic pattern is virtually pathognomonic and does not occur in essential hypertension. ### Why Paroxysmal Hypertension is the Best Discriminator 1. **Essential hypertension** produces sustained elevation; patients are hypertensive on every visit. 2. **Pheochromocytoma** produces dramatic swings: normal BP between attacks, severe hypertension during attacks. 3. This difference in **temporal pattern** is more specific than any single lab value or structural finding. ### High-Yield Mnemonic **Mnemonic — 5 P's of Pheochromocytoma:** Pressure (Paroxysmal), Perspiration, Palpitations, Pallor, Pounding headache — all episodic. ### Why Other Features Are Less Discriminating - **LVH and microalbuminuria** occur in both conditions (chronic hypertension sequelae). - **Elevated diastolic BP on office visits** is expected in essential hypertension but may be normal in pheochromocytoma between episodes.
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