How are pheochromocytomas diagnosed?

Pheochromocytomas, which are tumors arising from the adrenal medulla, are characterized by excessive production of catecholamines (like epinephrine and norepinephrine). Diagnosis is primarily based on detecting increased levels of metanephrines, which are metabolites of catecholamines.

The measurement of serum metanephrines is a sensitive method for detecting pheochromocytomas, and it can be complemented by a 24-hour urine collection to assess for elevated levels of metanephrines or catecholamines. This combination is highly effective because it captures potential fluctuations in hormone levels that could result from episodic release of catecholamines by the tumor.

While imaging studies such as a CT scan, MRI, and ultrasound can help visualize the tumor and confirm its status, they are not the primary means of diagnosis. Imaging may be more relevant for localization after biochemical confirmation of the disorder. The crucial step in establishing a diagnosis of pheochromocytoma revolves around demonstrating these increased metanephrine levels, making the measurement of serum and urine metanephrines the cornerstone of diagnosis.