• Study of adrenocortical-renin-angiotensin system
• Adrenal cortical function test
• Evaluate renal hypertension
• Diagnose Conn syndrome (primary aldosteronism)
• Evaluate hypokalemia with hypertension

• If patient is taking diuretics, antihypertensive drugs, cyclic progestational agents, estrogen, or licorice, results for aldosterone may not be interpretable
• Patient should be on a diet containing 135 mmol (3 g) sodium per day for at least two weeks and preferably 30 days prior to testing

24-hr urine collection container, no additive

Instruct the patient to void at 8 AM and discard the specimen. Then collect all urine including the final specimen voided at the end of the 24-hour collection period (ie, 8 AM the next morning) into the plastic urine container. Screw the lid on securely. Transport the specimen promptly to the laboratory.

Container MUST be labeled with patient's full name, date and time collection started, and date and time collection finished.

How to collect a 24-hr urine sample

1. Measure and record the total volume of 24-hour collection
2. Mix sample well
3. Transfer  a 10mL (minimum 1.0mL) aliquot to a Transfer vial/tube with cap - 12mL (LabCorp)

pH must be 4 to 8

Transfer vial/tube with cap - 12mL (LabCorp)

Refrigerated (preferred) - 14 days

Ambient - 7 days

Frozen - 14 days

• Incomplete 24-hour collection
• Original container with pH <2

Liquid chromatography/tandem mass spectrometry (LC/MS-MS)

Pediatric:
0 - 3 days:           0.00−5.00 μg/24 hrs
4 days - 10 years: 0.00−8.00 μg/24 hrs
>10 years:           0.00−19.00 μg/24 hrs

Adult:
Low sodium intake:     20.00−80.00 μg/24 hrs
Normal sodium intake:  0.00−19.00 μg/24 hrs
High sodium intake:      0.00−12.00 μg/24 hrs