|
|
|
|
Lab Dept:
|
Urine/Stool
|
Test Name:
|
ALDOSTERONE, TIMED URINE
|
General Information
|
Lab Order Codes:
|
UALD
|
Synonyms:
|
N/A
|
CPT Codes:
|
82088 – Aldosterone
82570 – Creatinine; other source
|
Test Includes:
|
Urine aldosterone concentrations in μg/g creatinine and μg/24 hours, urine creatinine concentration in mg/kg body weight/24 hours. Note: Creatinine excretion is dependent on body size.
|
Logistics
|
Test Indications:
|
When hyperaldosteronism is suspected, 24 hour urine for potassium provides a useful screening test following repletion of potassium and adequate intake.
|
Lab Testing Section:
|
Urine/Stool - Sendouts
|
Referred to:
|
Esoterix, Inc.(test #500018)
|
Phone Numbers:
Minneapolis:
Saint Paul:
|
|
612-813-6280
|
651-220-6550
|
Test Availability:
|
Daily, 24 hours
|
Turnaround Time:
|
3 - 8 days, test set up on Thursday
|
Special Instructions:
|
Submit an entire 24-hour urine collection. No preservative. Refrigerate specimen during and after collection.
Note: Starting and ending times of collection are required for a timed urine collection and must be documented electronically or on the proper request form.
|
Specimen
|
Specimen Type:
|
Urine, timed collection
|
Container:
|
Plastic leakproof container (No preservative). Urine GUARD® collection container is preferred for a timed urine sample.
|
Draw Volume:
|
Submit an entire 24-hour urine collection
|
Processed Volume:
|
50 mL (Minimum: 5.0 mL) aliquot of a well mixed 24 hour urine
|
Collection:
|
For timed urine collections, empty the bladder, discard the voided sample, and note the start time. Collect all urine voided for the specified time period. At the end of the period, note the finishing time, add the last voided sample to the container by emptying the bladder. Bring the refrigerated container to the lab. Make sure all specimens submitted to the laboratory are properly labeled with the patient’s name, medical record number and date of birth.
|
Special Processing:
|
Lab Staff: Add boric acid (0.5 g/100 mL) as preservative. Acidify urine to pH 4.0 with acetic acid. Do not use strong mineral acid. Indicate the 24-hour volume. Remove processed aliquot and freeze. Ship frozen. Forward promptly.
|
Patient Preparation:
|
Diuretics, antihypertensive drugs, cyclic progestogens, estrogens, and licorice should be terminated for at least 2 weeks and preferably 4 weeks prior to testing. Patient should be on a diet containing 135 mmol (3g) sodium/day for at least 2 weeks and preferably 30 days prior to testing. No recent radioactive scans. Potassium deficiencies should be corrected before specimen is collected.
|
Sample Rejection:
|
Unlabeled specimens
|
Interpretive
|
Reference Range:
|
Ad Lib Sodium Intake
|
Age
|
Aldosterone μg/24 hours
|
Aldosterone μg/g creatinine
|
Newborn:1-3 days
|
0.5 - 5
|
20 - 140
|
Prepubertal: 4-10 years:
|
1 - 8
|
4 - 22
|
Creatinine mg/kg body weight/24 hours:
|
16 – 22
Note: Creatinine excretion is dependent on body size
|
Critical Values:
|
N/A
|
Limitations:
|
Urinary aldosterone measurements alone are of very limited value in the diagnosis of hyperaldosteronism. Cushing's syndrome must be excluded with investigation for hyperaldosteronism.
|
Methodology:
|
RIA after selective solvent extraction
|
Contraindications:
|
N/A
|
References:
|
Esoteric, Inc. "Laboratory Services Test Directory” Web page www.esoterix.com
|
Esoteric, Inc. "Expected Value & S.I. Unit Conversion Table" Fifth Edition
|
Case Records of the Massachusetts General Hospital. Weekly Clinicopathological Exercises. Case 24-1992 (1992) A 52-Year-Old Man With Hypertension, Hypokalemia, and an Adrenal Mass, N Engl J Med 326(24):1617-23
|
