Patient Preparation
Supine: 1. Both specimens should be obtained between 8 am and 10 am (after at least 2 hours in supine position). 2. Normal sodium diet (100-200 mEq/day) for at least 3 days. 3. Receiving no medication known to affect renin-aldosterone system.
Upright: 1. Both specimens should be obtained before noon (after at least 2 hours in upright position, seated or standing). 2. Normal sodium diet (100-200 mEq/day) for at least 3 days. 3. Receiving no medication known to affect renin-aldosterone system.