Potassium, 24-Hour Urine
Use
Evaluate electrolyte balance, acid-base balance; evaluate hypokalemia; Carroll and Oh point out that urinary loss of 40 mmol/24 hours in the presence of hypokalemia 50 mmol/L in a hypokalemic, hypertensive patient not on a diuretic may indicate primary or secondary aldosteronism. The kidneys do not respond quickly to potassium deprivation. There is renal wastage of potassium in secondary aldosteronism. Glucocorticoids, including endogenous steroids in Cushing's syndrome, are among the causes of kaliuresis.
Special Instructions
Ensure the 24-hour urine collection is complete, and state the 24-hour volume on the test request form. Label the container with the patient's full name and the dates and times of the collection.
Limitations
The kidneys do not respond quickly to potassium deprivation, which should be considered when interpreting results. Urinary potassium may be elevated due to dietary intake, medications, or conditions such as hyperaldosteronism or renal tubular acidosis. Incomplete or inaccurately timed specimen collection can lead to misleading results.
Methodology
Automated Analyzer (Clinical Chemistry)
Biomarkers
LOINC Codes
- 2829-0
- 2828-2
- 2829-0
Result Turnaround Time
1 day
Related Documents
For more information, please review the documents below
Specimen
Urine
Volume
10 mL aliquot of entire collection
Minimum Volume
1 mL aliquot (Note: This volume does not allow for repeat testing.)
Container
Plastic urine container, no preservative
Collection Instructions
If the specimen is a 24-hour collection 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). Screw the lid on securely. Mix well. Container must be labeled with the patient's full name and dates and times of collections.
Storage Instructions
Maintain specimen at room temperature.
Causes for Rejection
Improper labeling
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |