An auxiliary test to fractionated plasma and urine metanephrine measurements in the diagnosis of pheochromocytoma and paraganglioma
An auxiliary test to urine vanillylmandelic acid and homovanillic acid determination in the diagnosis and follow-up of patients with neuroblastoma and related tumors
This assay is of greatest value when the specimen is collected during a hypertensive episode
Do not order this test on patients withdrawing from legal or illegal drugs known to cause rebound catecholamine release during withdrawal (see Limitations for details)
This test should not be used as the first-line test for pheochromocytoma. The recommended first-line laboratory tests for pheochromocytoma are PMET / Metanephrines, Fractionated, Free, Plasma and/or METAF / Metanephrines, Fractionated, 24 Hour, Urine
Specimen Type
24-Hr Urine
Specimen Collection / Processing Instructions
Discontinue drugs that release or hinder metabolism of epinephrine, norepinephrine, or dopamine for at least 1 week before specimen collection (see Limitations for details). If this is not possible for medical reasons, contact the laboratory to discuss whether a shorter drug-withdrawal period may be acceptable
Unless the reason for testing is drug monitoring, discontinue any epinephrine, norepinephrine, or dopamine injections or infusions for at least 12 hours before specimen collection
Collect urine for 24 hours
Add 25 mL of 50% acetic acid as preservative at start of collection (15 mL of 50% acetic acid for children < 5 years old). This preservative is intended to achieve a pH of between approximately 2 and 4.
Refrigerated (preferred): 7 days Frozen: 14 days Ambient: 7 days
Unacceptable Specimen Conditions
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.
Limitations
Many alterations in physiologic and pathologic states can profoundly affect catecholamine concentrations
Any environmental factors that may increase endogenous catecholamine production should be avoided. These include noise, stress, discomfort, body position, and the consumption of food, caffeinated beverages, and nicotine. Caffeine and nicotine effects are short term, a few minutes to hours only
Other substances and drugs that may affect the results include:
Substances that result in increased release or diminished metabolism of endogenous catecholamines:
Monamine oxidase inhibitors (MOIs): a class of anti-depressants with marked effects on catecholamine levels, particularly if the patient consumes tyrosine rich foods, such as nuts, bananas, or cheese
Catecholamine reuptake inhibitors including cocaine and synthetic cocaine derivatives, such as many local anesthetics, which also can be antiarrhythmic drugs (eg, lidocaine)
Some anesthetic gases, particularly halothane
Withdrawal from sedative drugs, medical or recreational, in particular alcohol, benzodiazepines (eg, Valium), opioids, and some central acting antihypertensive drugs, particularly Clonidine, but, generally not cannabis or other hallucinogens such as lysergic acid diethylamide (LSD), mescal, or peyote
Historically, a third category of potentially interfering substances was represented by molecules that are either similar in chemical structure, antibody epitopes, or chromatographic migration pattern to the catecholamines, or have metabolites that can be mistaken for the catecholamines. Our current HPLC-based assay is not subject to any significant direct interference of this kind. In most cases, the following drugs do not cause problems with the current assay that cannot be resolved: acetaminophen, allopurinol, amphetamines and its derivatives (methamphetamine, methylphenidate [Ritalin], fenfluramine, methylenedioxymethamphetamine [MDMA: ecstasy]), atropine, beta blockers (atenolol, labetalol, metoprolol, sotalol), buspirone, butalbital, carbamazepine, clorazepate, chlordiazepoxide, chlorpromazine, chlorothiazide, chlorthalidone, clonidine, codeine, diazepam, digoxin, dimethindene, diphenhydramine, diphenoxylate, dobutamine, doxycycline, ephedrine and pseudoephedrine, fludrocortisone, flurazepam, guanethidine, hydralazine, hydrochlorothiazide, hydroflumethiazide, indomethacin, insulin, isoprenaline, isosorbide dinitrate, L-Dopa, methenamine mandelate (mandelic acid), methyldopa, methylprednisolone, nitrofurantoin, nitroglycerine, oxazepam, entazocine, phenacetin, phenformin, phenobarbital, phenytoin, prednisone, probenecid, progesterone, propoxyphene, propranolol, quinidine, spironolactone, tetracycline, thyroxine, and tripelennamine
On occasion, when interference cannot be resolved, an interference comment will be reported
The variability associated with age, gender, and renal failure is uncertain
