Pheochromocytoma: Symptoms, Diagnosis, Treatment, and When to Suspect It

What Exactly Is a Pheochromocytoma?

Pheochromocytoma is a neuroendocrine tumor arising from chromaffin cells of the adrenal medulla. It secretes catecholamines, primarily epinephrine and norepinephrine, in bursts that drive dramatic cardiovascular instability. The related term paraganglioma refers to the same tumor type arising from extra-adrenal chromaffin tissue along the sympathetic chain. Clinicians sometimes group both under the shorthand PPGL (pheochromocytoma and paraganglioma).

The annual incidence sits at roughly 2, 8 cases per million people, yet autopsy series suggest up to 50% of pheochromocytomas are missed during life, making diagnostic suspicion the most important clinical skill [1]. Among patients investigated for secondary hypertension, approximately 0.2 to 0.6% will have a PPGL [2]. Because the tumors can cause sudden lethal hypertensive crisis, stroke, or arrhythmia, even a low pretest probability warrants biochemical screening when symptoms fit.

The adrenal medulla is not the same tissue as the adrenal cortex, which produces cortisol, aldosterone, and androgens. Diseases of the cortex, including Addison's disease (primary adrenal insufficiency) and Cushing's syndrome, arise from entirely different cell populations and carry different biochemical fingerprints. Pheochromocytoma originates in medullary chromaffin cells and does not primarily disrupt cortisol production, although large tumors that destroy the cortex can secondarily impair cortisol output [3].

Classic Symptoms: The Triad and Beyond

The textbook triad of episodic headache, diaphoresis, and palpitations occurs in roughly 40 to 50% of symptomatic patients and, when all three are present alongside hypertension, carries a positive likelihood ratio of approximately 6.7 for pheochromocytoma [4]. Hypertension itself may be paroxysmal (occurring in about 50% of cases) or sustained (about 50%), and a meaningful minority of patients are normotensive between episodes.

Other reported features include pallor (not flushing, which is more typical of carcinoid), anxiety or panic-like sensations, tremor, abdominal pain, and weight loss from catecholamine-driven hypermetabolism. Triggers reported by patients include positional changes, exercise, certain foods (tyramine-containing foods such as aged cheese), bladder distension, and direct tumor manipulation [5].

Paroxysms typically last 15 to 20 minutes and may occur daily or only a few times per year. The unpredictability is what makes the diagnosis so frequently delayed: mean time from symptom onset to diagnosis historically exceeds 3 years in registry data [6].

Patients with Cushing's syndrome, by contrast, present with weight gain, central obesity, purple striae, moon facies, and proximal myopathy driven by glucocorticoid excess. Patients with Addison's disease present with fatigue, hyperpigmentation, salt craving, and orthostatic hypotension from cortisol and aldosterone deficiency. These phenotypes overlap poorly with pheochromocytoma, though all three conditions can produce hypertension and electrolyte abnormalities and must be considered in any adrenal incidentaloma workup [7].

Who Should Be Screened?

Biochemical screening is warranted in four groups. First, patients with hypertension and the classic symptom triad. Second, patients with an incidentally discovered adrenal mass on imaging. Third, individuals with a known hereditary syndrome predisposing to PPGL: multiple endocrine neoplasia type 2 (MEN2, RET mutation), von Hippel-Lindau disease (VHL mutation), neurofibromatosis type 1 (NF1), or an SDHx (succinate dehydrogenase subunit) mutation [8]. Fourth, patients with a prior PPGL, given recurrence rates of 15 to 17% over 10 years [9].

The Endocrine Society's 2014 clinical practice guideline states: "We recommend biochemical testing for pheochromocytoma and paraganglioma in all patients with an adrenal incidentaloma" [10]. This applies even when imaging characteristics look benign, because a small fraction of lipid-rich adenoma-appearing masses will biochemically secrete.

Genetic testing deserves emphasis. A 2020 analysis of the COMETE network (N=1,124) found that 40% of apparently sporadic PPGLs carried a pathogenic germline variant when comprehensive gene panel testing was performed [11]. Routine germline testing is now recommended for all patients with confirmed PPGL regardless of family history or age at diagnosis [10].

Biochemical Diagnosis: Plasma vs. Urine Testing

Plasma free metanephrines (normetanephrine and metanephrine) are the single best initial test. A 2002 landmark study by Lenders et al. in JAMA (N=214) reported sensitivity of 97% and specificity of 93% for plasma free metanephrines versus 86% sensitivity and 88% specificity for urinary fractionated metanephrines [12]. Urine fractionated metanephrines collected over 24 hours remain a useful confirmatory or complementary test, particularly when false-positive plasma results are suspected.

Sources of false-positive elevation include tricyclic antidepressants, acetaminophen at high doses, levodopa, stimulant medications, and physiologic stress such as acute illness or hypoglycemia. The test should ideally be drawn after 20 to 30 minutes of supine rest in a low-stress setting [13].

A plasma normetanephrine greater than 2.5 times the upper limit of normal, or a plasma metanephrine greater than 2.0 times the upper limit of normal, is highly predictive of PPGL and warrants imaging without further biochemical workup. Borderline elevations (1.0, 2.5 times normal) may require clonidine suppression testing: failure of clonidine 0.3 mg to suppress plasma normetanephrine by more than 40% after 3 hours supports the diagnosis [14].

Twenty-four-hour urine catecholamines (epinephrine, norepinephrine, dopamine) and chromogranin A add information in selected cases, particularly for dopamine-secreting tumors, which are more common in SDH-mutated paragangliomas and may produce minimal or no metanephrine elevation [15].

Imaging: CT, MRI, and Functional Scans

Once biochemistry is positive, CT of the abdomen and pelvis with adrenal protocol (thin-slice, pre- and post-contrast with washout) is the first-line anatomic test. Pheochromocytomas typically appear as heterogeneous, hypervascular masses with absolute contrast washout below 60%, distinguishing them from the rapid washout seen in benign adenomas. MRI is preferred in pregnancy, in children, and when radiation minimization matters; pheochromocytomas classically show bright T2 signal, though this feature alone is not diagnostic [16].

For metastatic disease, extra-adrenal tumors, or when CT/MRI is inconclusive, functional imaging adds specificity. 123I-MIBG scintigraphy carries sensitivity of roughly 77 to 90% for localization of metastatic PPGL [17]. Ga-68 DOTATATE PET-CT is now considered superior for SDHx-mutated and metastatic PPGLs: a prospective study (N=78) showed DOTATATE PET sensitivity of 97% versus 74% for MIBG [18]. FDG-PET adds value in SDHB-mutated cases, which are the most aggressive subtype.

Pre-Operative Medical Management

Surgery without adequate adrenergic blockade carries a perioperative mortality rate historically as high as 25 to 50% from hypertensive crisis, arrhythmia, and cardiovascular collapse [19]. Alpha-blockade must be established before beta-blockade. Reversing this order risks unopposed alpha-receptor stimulation and severe hypertension.

Phenoxybenzamine, a non-competitive alpha-1 and alpha-2 blocker, is the most commonly used agent in North America. Typical dosing starts at 10 mg orally twice daily and titrates over 10 to 14 days to a target of mild orthostatic hypotension (systolic drop of 10 to 20 mmHg on standing) and nasal congestion as signs of adequate blockade. Total daily doses commonly reach 20 to 100 mg [20].

Selective alpha-1 blockers (doxazosin, prazosin, terazosin) are widely used in Europe and for patients who cannot tolerate phenoxybenzamine's side-effect profile. A 2017 meta-analysis of 7 comparative studies found no statistically significant difference in intraoperative hemodynamic instability between phenoxybenzamine and selective alpha-1 blockers (pooled OR 1.22 to 95% CI 0.67, 2.21, P<0.48), though individual trial sizes were small [21].

Beta-blockade (typically atenolol or metoprolol 25 to 50 mg daily) is added 2 to 3 days before surgery only after alpha-blockade is established, to control reflex tachycardia. High-sodium diet and liberal fluid intake (2, 3 liters per day) during the pre-operative period counteract the volume contraction caused by chronic catecholamine excess and reduce post-resection hypotension [22].

Calcium channel blockers (amlodipine, nicardipine) are used as adjuncts for residual blood pressure control and are the preferred agents in pregnancy, where phenoxybenzamine crosses the placenta [23].

Surgical Approach: Laparoscopic vs. Open Adrenalectomy

Laparoscopic adrenalectomy is the standard of care for tumors below 6 cm in size with no evidence of local invasion. A prospective comparison (N=300) published in the Annals of Surgery demonstrated shorter hospital stay (2.9 vs. 6.1 days), less blood loss, and equivalent recurrence rates compared with open adrenalectomy for sporadic pheochromocytoma [24].

Open adrenalectomy remains preferred for tumors above 6 to 8 cm, tumors with suspected capsular invasion or adjacent organ involvement, or when malignant paraganglioma requires extensive regional lymphadenectomy. The surgeon should handle the tumor as little as possible before the adrenal vein is ligated, to prevent intraoperative catecholamine surges. An experienced anesthesia team with invasive arterial monitoring and vasopressors on standby (phenylephrine or norepinephrine infusions) is mandatory [25].

Cortisol-sparing adrenalectomy (partial resection) is considered in bilateral pheochromocytoma, as seen in MEN2A and VHL, to preserve adrenocortical function and avoid lifelong glucocorticoid replacement. This approach carries approximately 10 to 15% risk of local recurrence, which must be weighed against the morbidity of Addison-like adrenal insufficiency from bilateral total adrenalectomy [26].

Malignant Pheochromocytoma: Definition and Treatment

No histologic feature reliably predicts malignancy. The only accepted definition of malignant pheochromocytoma is the presence of metastases at sites where chromaffin tissue is not normally found, such as liver, lung, lymph nodes, or bone [27]. SDHB mutation is the strongest predictor of malignant behavior, conferring a malignancy rate of 31 to 71% in published series compared with approximately 3 to 4% in sporadic tumors [28].

First-line therapy for metastatic PPGL is 131I-MIBG, which produces partial or complete response in 30 to 40% of patients with MIBG-avid disease. A phase 2 study (N=68, PRRT study, NCT01141919) of high-specific-activity 131I-MIBG (Azedra, iobenguane I-131) demonstrated an objective response rate of 23% with a median duration of 21.9 months; FDA approved this agent in 2018 specifically for MIBG-avid unresectable pheochromocytoma [29].

Combination chemotherapy with cyclophosphamide, vincristine, and dacarbazine (CVD regimen) produces objective responses in approximately 37% of patients with malignant PPGL in the largest retrospective series, though responses are often partial and durable responses are uncommon [30]. Sunitinib, a multi-kinase inhibitor, showed disease stabilization in a phase 2 trial (N=25) with a progression-free survival of 13.4 months in SDHB-mutated metastatic paraganglioma [31].

Distinguishing Pheochromocytoma from Other Adrenal Conditions

Addison's Disease (Primary Adrenal Insufficiency)

Addison's disease results from autoimmune destruction of all three cortical zones, reducing cortisol, aldosterone, and adrenal androgens simultaneously. The Endocrine Society's 2016 guideline defines the biochemical diagnosis as a peak cortisol below 18 mcg/dL (500 nmol/L) on a 250-mcg cosyntropin stimulation test, alongside an elevated morning ACTH (typically above 100 pg/mL) [32]. Hyperpigmentation results from compensatory ACTH and MSH excess. Plasma metanephrines are normal. The conditions share hypovolemia and hemodynamic instability as features, but Addison's disease produces hypotension from mineralocorticoid deficiency rather than hypertension from catecholamine excess.

Secondary Adrenal Insufficiency

Secondary adrenal insufficiency stems from pituitary ACTH deficiency, often from corticosteroid suppression or a pituitary mass. Unlike Addison's disease, aldosterone secretion remains largely intact (it is regulated by the renin-angiotensin system, not ACTH), so hyperpigmentation and hyperkalemia are absent. Cortisol response to cosyntropin stimulation may be blunted. Plasma metanephrines are normal, and hypertension is not a feature [33].

Cushing's Syndrome and Cushing's Disease

Cushing's syndrome denotes glucocorticoid excess from any cause: exogenous steroids, adrenal adenoma or carcinoma, or ectopic ACTH. Cushing's disease specifically refers to pituitary ACTH-secreting adenoma driving bilateral adrenal cortical hyperplasia. The Endocrine Society's 2008 guideline recommends initial screening with either late-night salivary cortisol, 24-hour urinary free cortisol, or 1-mg overnight dexamethasone suppression test [34]. In Cushing's disease, ACTH is elevated but not as dramatically suppressed by high-dose (8-mg) dexamethasone as in ectopic ACTH. MRI of the pituitary identifies a discrete adenoma in only 60 to 70% of confirmed Cushing's disease cases, requiring bilateral inferior petrosal sinus sampling when MRI is non-localizing [35].

Pheochromocytoma can rarely co-secrete ACTH (ectopic ACTH syndrome), causing a combined phenotype of severe hypertension and rapid-onset Cushing's features. This combination should prompt urinary cortisol and plasma metanephrine testing simultaneously [36].

Post-Surgical Follow-Up

Biochemical cure is defined as normalization of plasma or urine metanephrines at 2 to 6 weeks post-resection. Persistent elevation suggests residual tumor, incomplete resection, or occult metastatic disease. Long-term follow-up is lifelong, given the 15 to 17% recurrence risk and the possibility of delayed metastasis appearing years after apparently curative resection [37].

Annual plasma free metanephrines and blood pressure measurement for at least 10 years post-resection is recommended by the Endocrine Society. Patients with hereditary syndromes require annual surveillance indefinitely. Imaging (CT or MRI) is indicated if biochemistry recurs or new symptoms develop; routine surveillance imaging in asymptomatic biochemically normal patients is not supported by current evidence [10].

Quality-of-life data from the prospective ENSAT registry (N=201) showed that approximately 25% of patients treated for pheochromocytoma report residual hypertension requiring medication at 1 year post-surgery, and 12% report persistent fatigue affecting daily function [38].

HealthRX Clinical Decision Framework: When to Test for Pheochromocytoma

The following three-tier screening logic reflects current Endocrine Society and European Society of Endocrinology guidance, adapted to the clinical presentation patterns seen most commonly in telehealth hypertension evaluations:

Tier 1 (test immediately): Any patient with hypertensive crisis (systolic above 180 mmHg) plus at least one of headache, sweating, or palpitations. Order plasma free metanephrines and 24-hour urine fractionated metanephrines together. Do not delay for an outpatient visit.

Tier 2 (test within 2 weeks): Patients with a newly discovered adrenal incidentaloma of any size on cross-sectional imaging, patients with difficult-to-control hypertension on three or more drugs, and patients with a known hereditary PPGL syndrome regardless of symptom status.

Tier 3 (consider testing): Patients with episodic symptoms (panic attacks, palpitations, unexplained diaphoresis) and normal resting blood pressure but at least one family member with a hereditary endocrine tumor syndrome. Clonidine suppression testing may clarify borderline biochemical results before committing to adrenal imaging.

Managing the Incidental Adrenal Mass

Adrenal incidentalomas (masses found incidentally on imaging ordered for another reason) occur in 3 to 7% of CT scans performed in adults over age 50 [39]. The differential is broad: non-functioning cortical adenoma (most common), cortisol-secreting adenoma, primary aldosteronism, adrenocortical carcinoma, pheochromocytoma, and metastasis. The American Association of Clinical Endocrinology and the Endocrine Society both recommend the same initial biochemical panel for any adrenal incidentaloma above 1 cm: plasma free metanephrines, 1-mg overnight dexamethasone suppression test, and (if hypertension or hypokalemia is present) plasma aldosterone-to-renin ratio [7].

Imaging characteristics guide the malignancy risk assessment. Unenhanced CT attenuation above 10 Hounsfield units, heterogeneous texture, size above 4 cm, or irregular margins each increase concern and may prompt surgical referral even before biochemical confirmation of secretion. A purely incidental, non-secreting, homogeneous mass below 4 cm with attenuation under 10 HU can be followed with repeat imaging at 6 and 24 months if stable [7].

Repeat biochemical testing annually for 4 years is recommended even for biochemically silent incidentalomas, because a small proportion will develop secretory activity on follow-up [40].

Plasma free metanephrines should be the test ordered at every follow-up visit for any adrenal incidentaloma, regardless of prior negative results. The diagnostic yield of repeat testing in growing or changing adrenal masses is approximately 3 to 5% per year in registry data [40].