Figure 431

Screening and diagnostic tests in pheochromocytoma. Drugs, incomplete urine collection, and episodic secretion of catecholamines can influence the tests based on 24-hour urine collections in a patient with a pheochromocytoma. The clonidine suppression test is fraught with false-negative and false-positive results that are unacceptably high for the exclusion of this potentially fatal tumor. The "sleep" norepinephrine test eliminates the problems of incomplete 24-hour urine collection because the patient discards all urine before retiring; saves all urine voided through the sleep period, including the first specimen on arising; and notes the elapsed (sleep) time [10]. The sleep period is typically a time of basal activity of the sympathetic nervous system, except in patients with pheochromocytoma (see Fig. 4-32).

0 0

Post a comment