What is the most sensitive screening approach for pheochromocytoma in pregnancy?

What is the most sensitive screening approach for pheochromocytoma in pregnancy?

• A. 24-hour urinary metanephrines
• B. Plasma-free metanephrines
• C. Plasma free catecholamines
• D. Imaging with ultrasound

Answer: (B)

Plasma-free metanephrines are the most sensitive screening approach for pheochromocytoma in pregnancy. Metanephrines are produced continuously by the tumor and surrounding tissues, so measuring them in plasma captures this ongoing production more reliably than relying on episodic catecholamine surges. The plasma-free test, typically measured with LC-MS/MS, tends to have the highest sensitivity and is less affected by short-lived stress or postural changes than other tests. In contrast, 24-hour urinary metanephrines depend on complete urine collection and can miss intermittent secretion or be biased by collection inaccuracies. Plasma free catecholamines are more variable because they reflect acute states and can be influenced by stress, medications, or sampling conditions, making them less dependable for screening. Imaging with ultrasound can help localize a tumor but is not a screening test for catecholamine excess and is used after biochemical confirmation. For these reasons, plasma-free metanephrines provide the best balance of sensitivity and practicality for initial screening in pregnancy.

Plasma-free metanephrines are the most sensitive screening approach for pheochromocytoma in pregnancy. Metanephrines are produced continuously by the tumor and surrounding tissues, so measuring them in plasma captures this ongoing production more reliably than relying on episodic catecholamine surges. The plasma-free test, typically measured with LC-MS/MS, tends to have the highest sensitivity and is less affected by short-lived stress or postural changes than other tests. In contrast, 24-hour urinary metanephrines depend on complete urine collection and can miss intermittent secretion or be biased by collection inaccuracies. Plasma free catecholamines are more variable because they reflect acute states and can be influenced by stress, medications, or sampling conditions, making them less dependable for screening. Imaging with ultrasound can help localize a tumor but is not a screening test for catecholamine excess and is used after biochemical confirmation. For these reasons, plasma-free metanephrines provide the best balance of sensitivity and practicality for initial screening in pregnancy.