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, 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 anti-arrhythmic drugs (e.g., lidocaine)
- Some anesthetic gases, particularly halothane
- Withdrawal from sedative drugs, medical or recreational, in particular alcohol, benzodiazepines (e.g., 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
- Vasodilating drugs (e.g., calcium antagonists, alpha-blockers)
- Tricyclic antidepressants usually exert a negligible effect
Substances that reduce or increase plasma volume acutely (e.g., diuretics, radiographic contrast media, synthetic antidiuretic hormone[e.g., desmopressin 1-deamino-8-d-arginine vasopressin, DDAVP])
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 high-pressure liquid chromatography (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, pentazocine, phenacetin, phenformin, phenobarbital, phenytoin, prednisone, probenecid, progesterone, propoxyphene, propranolol, quinidine, spironolactone, tetracycline, thyroxine, and tripelennamine.
On occasion, when an interference cannot be resolved, an interference comment will be reported.
The variability associated with age, gender, and renal failure is uncertain.