Endocrinology · Adrenal Disorders
The facts most likely to be tested
The classic clinical triad of episodic headache, diaphoresis, and tachycardia in a patient with paroxysmal hypertension is highly suggestive of pheochromocytoma.
Initial diagnostic screening requires measuring plasma free metanephrines or 24-hour urine fractionated metanephrines and catecholamines.
Imaging for localization of the tumor is performed with CT or MRI of the abdomen and pelvis only after biochemical confirmation of the diagnosis.
Preoperative management mandates the initiation of alpha-adrenergic blockade (e.g., phenoxybenzamine) at least 7–14 days prior to surgery to prevent hypertensive crisis.
Beta-blockers must never be administered until adequate alpha-blockade is established to avoid unopposed alpha-adrenergic stimulation and subsequent life-threatening hypertension.
Pheochromocytoma is frequently associated with genetic syndromes, specifically MEN 2A and 2B, von Hippel-Lindau disease, and Neurofibromatosis type 1.
Definitive treatment for a localized pheochromocytoma is surgical resection following appropriate medical stabilization.
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A 34-year-old male presents to the clinic with a 3-month history of intermittent episodes of throbbing headaches, palpitations, and profuse sweating. He reports these episodes last approximately 20 minutes and are associated with a sense of impending doom. Physical examination reveals a blood pressure of 178/102 mmHg, which decreases to 135/85 mmHg after the episode resolves. He has a family history of medullary thyroid carcinoma in his mother. Laboratory studies show elevated plasma free metanephrines.
Which of the following is the most appropriate next step in management before surgical intervention?
Initiation of phenoxybenzamine
The patient presents with classic symptoms of pheochromocytoma, likely associated with MEN 2A. The most critical step before surgery is establishing alpha-blockade to prevent a hypertensive crisis during tumor manipulation.
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High yield triage
Etiology / Epidemiology
Catecholamine-secreting tumor of the adrenal medulla; 10% are familial, often associated with MEN 2A/2B, von Hippel-Lindau, or Neurofibromatosis type 1.
Clinical Manifestations
Classic triad of episodic headache, sweating, and tachycardia; suspect in patients with refractory hypertension.
Diagnosis
Initial screen with plasma fractionated metanephrines; confirm with 24-hour urinary fractionated metanephrines and catecholamines.
Treatment
Preoperative alpha-blockade (e.g., phenoxybenzamine) is mandatory; never initiate beta-blockers before alpha-blockade.
Prognosis
Surgical resection is curative; 10% rule (10% malignant, 10% bilateral, 10% extra-adrenal, 10% pediatric).
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Epidemiology & Etiology
Most cases are sporadic, but 25-30% are linked to germline mutations in syndromes like MEN 2A/2B. The tumor arises from chromaffin cells of the adrenal medulla. Always screen for genetic associations in patients with bilateral or extra-adrenal tumors.
Pertinent Anatomy
Tumors are primarily located in the adrenal medulla, but 10% arise from extra-adrenal sympathetic ganglia known as paragangliomas. These extra-adrenal sites include the Organ of Zuckerkandl near the aortic bifurcation.
Pathophysiology
Excessive secretion of epinephrine and norepinephrine leads to systemic vasoconstriction and cardiac stimulation. This results in paroxysmal hypertension, which can be triggered by anesthesia, exercise, or trauma. Chronic exposure leads to volume depletion due to persistent vasoconstriction.
Clinical Manifestations
Patients present with the classic triad: episodic headache, diaphoresis, and tachycardia. Hypertensive crisis is a common presentation, often precipitated by medications or surgery. Look for orthostatic hypotension due to chronic volume contraction. Do not palpate the abdomen as it may trigger a massive catecholamine release.
Diagnosis
The plasma fractionated metanephrines test is the most sensitive initial screening tool. If positive, confirm with 24-hour urinary fractionated metanephrines and catecholamines. Once biochemical diagnosis is established, localize with CT or MRI of the abdomen/pelvis.
Treatment
Initiate phenoxybenzamine (non-selective alpha-blocker) 7-14 days prior to surgery to control blood pressure and expand intravascular volume. Beta-blockers (e.g., propranolol) must never be used first as they cause unopposed alpha-adrenergic vasoconstriction, leading to a hypertensive crisis. Surgical adrenalectomy is the definitive treatment.
Prognosis
Most patients achieve normotension post-resection, though some develop persistent hypertension. Long-term follow-up is required to monitor for recurrence or metastatic disease. Malignancy is defined by the presence of metastases in non-chromaffin tissues.
Differential Diagnosis
Essential hypertension: lacks paroxysmal symptoms and elevated metanephrines
Hyperthyroidism: presents with tachycardia/sweating but lacks episodic hypertension
Carcinoid syndrome: associated with flushing and diarrhea, not paroxysmal hypertension
Panic disorder: mimics symptoms but lacks biochemical evidence of catecholamine excess
Cocaine/Amphetamine use: causes sympathetic surge; screen urine toxicology if suspected