Special Instructions Note on requisition if patient was on a normal or low salt diet the previous 2-4 weeks, the site of collection, and if the patient was upright or supine for 4 hours before the blood was drawn.
Storage Instructions Transport specimen on ice to the laboratory immediately. Separate serum from cells within 30 minutes.
Patient Preparation Patient must avoid having radioisotope scan 24 hours prior to venipuncture. Patient should be in either supine or upright position 2 hours before and during blood drawing. All diuretics, antihypertensive drugs, cyclic progestogens, estrogens, and licorice should be terminated 2-4 weeks before this evaluation. Patient should be on a normal sodium diet for 2-4 weeks (135 mmol or 3 g sodium per day). Circadian rhythm exists in normal subjects, peaking in the morning.
Causes for Rejection Patient not prepared properly, specimen more than 30 minutes in transit
Reference Range Varies with sodium intake; on a normal sodium intake of 100-200 mEq/day: supine: <16 ng/dL, upright: 4-31 ng/dL
Use Evaluate patients with hypertension for primary hyperaldosteronism. Suppressed plasma renin activity suggests primary hyperaldosteronism in a hypertensive subject with renal potassium wasting.
