A 50-year-old man consults you because he has been having transient periods of rapid hea beat accompanied by sweating, flushing, and a sense of impending doom. Examination is unrevealing, with no evidence of arrhythmia at the time of the exam. However, the man&;s wife is a nurse, so the physician asks that she take vital signs the next time one of the episodes occurs. She does, and demonstrates a BP of 195/140 with hea rate 160/min during the episode. She promptly brings him to you, but the spell is over by the time that he is seen. Urinary measurement of which of the following would most likely be diagnostic in this case

**Core Concept**
The patient's symptoms are indicative of a condition characterized by episodic hypertension, tachycardia, and anxiety, which are hallmarks of a neurogenic disorder. The condition is associated with an abnormality in the regulation of blood pressure and heart rate, leading to episodes of hypertension and tachycardia.

**Why the Correct Answer is Right**
The patient's symptoms and the wife's observation of elevated blood pressure and heart rate during the episode are consistent with a diagnosis of **pheochromocytoma**. Pheochromocytomas are rare, catecholamine-secreting tumors that arise from the adrenal medulla. The excess catecholamines (e.g., epinephrine and norepinephrine) cause episodic hypertension, tachycardia, and anxiety. The urinary measurement of **metanephrines** would be diagnostic in this case, as it is a sensitive marker for pheochromocytoma.

* **Option A:** Free cortisol is not directly related to the symptoms described, and urinary free cortisol is more commonly used to diagnose Cushing's syndrome.
* **Option B:** Vanillylmandelic acid (VMA) is a metabolite of catecholamines, but it is not as sensitive or specific as metanephrines for diagnosing pheochromocytoma.
* **Option D:** Aldosterone is a hormone involved in regulating sodium and potassium balance, but it is not directly related to the symptoms described.

**Clinical Pearl / High-Yield Fact**
Pheochromocytomas can be associated with a syndrome of paroxysmal hypertension, tachycardia, and anxiety, and are often diagnosed incidentally during evaluation for hypertension. The key to diagnosis is the episodic nature of the symptoms and the presence of elevated catecholamines or their metabolites.

**Correct Answer:** B. Vanillylmandelic acid (VMA)

✓ Correct Answer: D. Vanillylmandelic acid VMA