Final answer:
The best single screening test for pheochromocytoma using 24-hour urine is to measure the levels of urinary metanephrines and/or catecholamines.
Step-by-step explanation:
The best single screening test for pheochromocytoma using 24-hour urine is to measure the levels of urinary metanephrines and/or catecholamines.
To do this, a 24-hour urine collection is performed, and the levels of metanephrines and/or catecholamines in the urine are measured using high-performance liquid chromatography (HPLC) or mass spectrometry (MS) techniques. This provides a reliable and accurate assessment of the presence of pheochromocytoma.