3 ml Plasma in 1 Lavender Top (EDTA) tube. and 2 ml Serum in 1 Red Top ( plain ) tube
Preparations Required
Patients should be upright or ambulatory for at least 2 hours before sampling. Note drug interactions: discontinue potassium-wasting diuretics, Spironolactone, Eplerenone, Amiloride, and Triamterene for 4 weeks; and Adrenergic blockers, Clonidine, Methyldopa, NSAIDs, ACE inhibitors, ARBs, Renin inhibitors, and Dihydropyridine calcium channel blockers for 2 weeks. If blood pressure control is necessary, alternative antihypertensives like Verapamil slow-release, Hydralazine, Prazosin, Doxazosin, or Terazosin may be used, as they minimally affect plasma renin and aldosterone. All medication changes should be done under physician guidance.