Pathology The most reliable test in the diagnosis of pheochromocytoma is A 24 hour urinary metanephrine B Urinary catecholamines C Urinary catecholamines D Basal plasma catecholamines 💡 Explanation The most reliable test in the diagnosis of pheochromocytoma is ✓ Correct Answer: A. 24 hour urinary metanephrine