A second-order screening test for the presumptive diagnosis of pheochromocytoma in patients with nonepisodic hypertension
Confirming positive plasma metanephrine results in patients with nonepisodic hypertension
Specimen Collection / Processing Instructions
Patient Preparation: Tricyclic antidepressants and labetalol and sotalol (beta blockers) may elevate levels of metanephrines. If clinically feasible, these medications should be discontinued at least 1 week before collection
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability
This test utilizes a liquid chromatography tandem mass spectrometry (LC-MS/MS) method and is not affected by the interfering substances that affected the previously utilized spectrophotometric (Pisano reaction) method (ie, diatrizoate, chlorpromazine, hydrazine derivatives, imipramine, monamine oxidase [MAO] inhibitors, methyldopa, phenacetin, ephedrine, or epinephrine)
This method is also not subject to the known interference of acetaminophen (seen with the plasma metanephrine HPLC-EC method)
When N-acetylcysteine is administered at levels sufficient to act as an antidote for the treatment of acetaminophen overdose, it may lead to falsely decreased creatinine results.