What are the diagnostic criteria for pheochromocytoma (adrenal gland tumor)?

From the Guidelines

Diagnosis of pheochromocytoma requires a combination of biochemical testing and imaging studies, with plasma free metanephrines or 24-hour urinary fractionated metanephrines being the most sensitive tests for detecting catecholamine-secreting tumors, as recommended by the most recent study 1. The diagnostic criteria for pheochromocytoma involve a step-wise approach, starting with biochemical testing to detect excess catecholamines or their metabolites.

• The initial evaluation should include measurement of plasma free metanephrines or 24-hour urinary fractionated metanephrines and catecholamines, which have a sensitivity of approximately 96-100% and are preferred as the first-line test 1.
• If biochemical testing is positive, anatomical localization should be performed using CT or MRI of the abdomen and pelvis, with CT having a sensitivity of about 90% for adrenal pheochromocytomas.
• For extra-adrenal tumors or metastatic disease, functional imaging with 123I-MIBG scintigraphy, 18F-FDG PET/CT, or 68Ga-DOTATATE PET/CT may be necessary.
• Genetic testing should be considered for all patients with pheochromocytoma, as approximately 40% have an underlying germline mutation in susceptibility genes such as RET, VHL, NF1, SDHA, SDHB, SDHC, SDHD, TMEM127, or MAX. Key points to consider in the diagnosis of pheochromocytoma include:
• The high morbidity and mortality associated with untreated pheochromocytomas, emphasizing the importance of early detection and treatment 1.
• The potential for pheochromocytomas to cause life-threatening hypertensive crises if not identified before procedures or surgery, highlighting the need for careful preoperative management with alpha-adrenergic blockade followed by beta-blockade to prevent cardiovascular complications.
• The importance of a multidisciplinary approach to the diagnosis and management of pheochromocytoma, involving endocrinologists, surgeons, and radiologists, as recommended by the most recent study 1.

From the Research

Diagnostic Criteria for Pheochromocytoma

The diagnostic criteria for pheochromocytoma involve a combination of biochemical tests, imaging studies, and clinical evaluation. The key steps in diagnosing pheochromocytoma are:

• Biochemical testing to confirm the presence of excess catecholamines or their metabolites (metanephrines) in the blood or urine 2, 3, 4, 5, 6
• Imaging studies such as computed tomography (CT) or magnetic resonance imaging (MRI) to localize the tumor 2, 4, 5, 6
• Functional imaging tests like scintigraphy with (123)I-metaiodobenzylguanidine (MIBG) or positron emission tomography (PET) to confirm the diagnosis 2, 4, 6

Biochemical Tests

The biochemical tests used to diagnose pheochromocytoma include:

• Measurement of plasma free metanephrines, which has a high sensitivity and specificity for the diagnosis 3, 4, 5
• Measurement of urinary fractionated metanephrines, which is also a sensitive and specific test 2, 3, 4, 5
• Measurement of plasma catecholamines, which can be used to confirm the diagnosis but has a lower sensitivity and specificity than metanephrine measurements 3, 5
• Measurement of urinary vanillylmandelic acid, which has a lower sensitivity and specificity than metanephrine measurements but can be used as a screening test 3

Imaging Studies

The imaging studies used to localize pheochromocytoma include:

• CT scan, which is highly sensitive and specific for localizing adrenal tumors 2, 4, 5, 6
• MRI, which is also highly sensitive and specific for localizing adrenal tumors 2, 4, 5, 6
• MIBG scan, which is highly specific for pheochromocytoma but has a lower sensitivity than CT or MRI 2, 4, 6
• PET scan, which can be used to localize metastatic disease or to confirm the diagnosis in cases where other imaging studies are negative 2, 4, 6

Clinical Evaluation

The clinical evaluation of patients with suspected pheochromocytoma includes:

• A thorough medical history to identify symptoms such as headaches, palpitations, and hypertension 2, 4, 5, 6
• A family history to identify patients with a genetic predisposition to pheochromocytoma 2, 4, 5, 6
• A physical examination to identify signs of catecholamine excess such as hypertension and tachycardia 2, 4, 5, 6