Mecholyl testA provocative test for pheochromocytoma in which 25 mg mecholyl evokes increased blood pressure in most patients with pheochromocytoma and a fall in pressure in normal subjects.
Because of the potential hazard associated with induction of a severe (hypertensive) paroxysm, provocative tests are almost never indicated; in a patient with paroxysmal symptoms and normal or borderline catecholamine excretion, it is preferable to document an increase in catecholamine excretion around the time of the crisis by sequential timed urine collections.
A test of parasympathetic nervous system function. A 2% solution of methacholine (Mecholyl) is instilled in the conjunctival sac. The pupil constricts if the patient has a parasympathetic disorder, such as familial dysautonomia.