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Special Instructions
State 24-hour volume on the test request form.
Expected Turnaround Time
Within 1 day
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Information
Related Documents
Specimen Requirements
Specimen
Urine (24-hour)
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
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.
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 14 days |
Refrigerated | 14 days |
Frozen | 14 days |
Freeze/thaw cycles | Stable x3 |
Causes for Rejection
Improper labeling
Test Details
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 <3 mmol/L is excessive.1 In the presence of such hypokalemia, urine excretion is helpful to separate renal from nonrenal losses. Excretion <20 mmol/24 hours is evidence that hypokalemia is not from renal loss.1 Renal loss >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.
Methodology
Ion-selective electrode (ISE); flame photometer
Reference Interval
See table.
Age | Male (mmol/24 hr) | Female (mmol/24 hr) |
|---|---|---|
0 to 5 y | Not established | Not established |
6 to 17 y | 11-88 | 10-70 |
18 to 80 y | 20-116 | 14-95 |
>80 y | 16-83 | 6-67 |
Additional Information
Urinary potassium may be elevated with dietary (food and/or medicinal) increase, hyperaldosteronism, renal tubular acidosis, onset of alkalosis, and with other disorders. Time relationships are important in interpretation. Potassium will decrease in Addison's disease and in renal disease with decreased urine flow (nephrosclerosis, pyelonephritis, glomerulonephritis).
Footnotes
1. Carroll HJ, Oh MS. Water Electrolyte and Acid-Base Metabolism: Diagnosis and Management. Philadelphia, Pa: JB Lippincott Co;1978.
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 003186 | Potassium, 24 hr Urine | 2829-0 | 013334 | Potassium, Urine | mmol/L | 2828-2 |
| 003186 | Potassium, 24 hr Urine | 2829-0 | 013276 | Potassium, Urine | mmol/24 hr | 2829-0 |
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