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HelpTest Code UPH24 pH, 24 Hour, Urine
Reporting Name
pH, 24 HR, UUseful For
Assessment of patients with metabolic acidosis, crystalluria, as well as monitoring the effectiveness of alkalinization or acidification of urine for certain medical conditions (eg, treatment of uric acid nephrolithiasis) using a 24-hour collection period
Method Name
pH Meter
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
UrineNecessary Information
24-Hour volume (in milliliters) is required.
Specimen Required
Supplies:
Diazolidinyl Urea (Germall), 5.0 mL (T822)
Urine Tubes, 10 mL (T068)
Container/Tube: Plastic, 10-mL urine tube or a clean, plastic aliquot container
Specimen Volume: 10 mL
Collection Instructions:
1. Collect urine for 24 hours
2. Add 5 mL of diazolidinyl urea as preservative at start of collection or refrigerate specimen during and after collection.
3. Specimen pH should be between 4.5 and 8 and will stay in this range if kept refrigerated. Specimens with pH >8 indicate bacterial contamination, and testing will be cancelled. Do not attempt to adjust pH as it will adversely affect results.
Additional Information: See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens for multiple collections.
Specimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated (preferred) | 7 days | |
| Frozen | 7 days |
Reject Due To
| All specimens will be evaluated at Mayo Clinic Laboratories for test suitability. |
Special Instructions
Reference Values
4.5-8.0
Day(s) Performed
Monday through Sunday
CPT Code Information
83986
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| UPH24 | pH, 24 HR, U | 27378-9 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| PH24 | pH, 24 HR, U | 27378-9 |
| TM90 | Collection Duration | 13362-9 |
| VL72 | Volume | 3167-4 |
Clinical Information
Urine pH is a measure of the acidity/alkalinity of urine and, by itself, usually provides little useful information. Under normal conditions its value is influenced by the type of diet. Some diets (eg, diets rich in meat) have more acid content than others (eg, vegetarian diets).
Changes in urine pH may reflect systemic acid-base disorders. For example, the normal response during metabolic acidosis is a lowering of the urine pH to less than 5. If the pH is greater than 5, then a defect in urine acidification should be considered. A urine pH of greater than 8 is suggestive of infection by a urea-splitting organism such as Proteus mirabilis.
Therapeutic interventions to either alkalinize or acidify the urine are necessary for some diseases. For example, some crystals have a propensity to form in alkaline urine, while others form in relative acidic urine, and changing the pH may reduce stone formation.
Interpretation
Dependent on clinical condition.
A pH greater than 8 suggests the presence of urinary tract infection with a urea-splitting organism.
Cautions
No significant cautionary statements
Method Description
The pH meter is composed of a glass electrode, calomel electrode and voltmeter. The glass electrode has a fixed acid concentration, yielding a corresponding voltage. The calomel electrode is the reference electrode. Its voltage is independent of the H+ ion concentration. The two electrodes constitute a galvanic cell whose electromotive force is measured by the voltmeter. The meter is calibrated to read in pH units, reflecting the H+ ion concentration. The meter is used to determine pH in 0 to 14 range.(Instruction manual: Fisher Scientific accumet Basic (AB) Benchtop Meters. Fisher Scientific; 68x613601.0 07/2012)