3 ML (2.5 ML MIN.) PLASMA FROM 1 LAVENDER TOP (EDTA) TUBE. PATIENT SHOULD BE AMBULATORY / UPRIGHT 2 HOURS PRIOR TO THE TEST. SEPARATE PLASMA AND FREEZE. SHIP FROZEN. DRUG INTERACTIONS TO BE NOTED: POTASSIUM WASTING DIURETICS, SPIRONOLACTONE, EPLERENONE, AMILORIDE AND TRIAMTERENE SHOULD BE DICONTINUED AT LEAST FOR 4 WEEKS; ADRENERGIC BLOCKERS, CLONIDINE, METHYLDOPA, NSAIDS, ANGIOTENSIN-CONVERTING ENZYME INHIBITORS, ANGIOTENSIN RECEPTOR BLOCKERS, RENIN INHIBITORS AND DIHYDROPYRIDINE CALCIUM CHANNEL ANTAGONISTS SHOULD BE DISCONTINUED FOR 2 WEEKS. IF NECESSARY TO MAINTAIN HYPERTENSION CONTROL, PATIENTS SHOULD BE TREATED WITH OTHER ANTIHYPERTENSIVE MEDICATIONS LIKE VERAPAMIL SLOW-RELEASE, HYDRALAZINE, PRAZOSIN, DOXAZOSIN & TERAZOSIN THAT HAVE LESSER EFFECTS ON PLASMA RENIN LEVELS. ANY CHANGE IN MEDICATION SHOULD BE DONE IN CONSULTATION WITH TREATING CLINICIAN.