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HelpTest ID: 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
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.
Special Instructions
Report Available
1 to 3 daysDay(s) Performed
Monday through Sunday
Clinical Reference
1. Menezes CJ, Worcester EM, Coe FL, Asplin J, Bergsland KJ, Ko B: Mechanisms for falling urine pH with age in stone formers. Am J Physiol Renal Physiol. 2019 Jul 1;317(7):F65-F72
2. Ilyas R, Cho K, Young JG: What is the best method to evaluate urine pH? A trial of three urinary pH measurement methods in a stone clinic. J Endourol. 2015 Jan;29(1):70-74
3. Davidsohn I, Henry JB: Todd-Sanford Clinical Diagnosis by Laboratory Methods. 15th ed. Elsevier; 1974; 43-44
4. Free AH, Free HBS: Urodynamics, concepts relating to urinalysis. Ames Co; 1974:57-61
5. Kaplan LA, Pesce AJ: Clinical Chemistry: Theory, Analysis, Correlation. 3rd ed. Mosby-Year Book Inc; 1996:823
Method Name
pH Meter
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 |
|---|---|---|
| Urine | Refrigerated (preferred) | 7 days |
| Frozen | 7 days |
Reference Values
4.5-8.0
Test Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.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 |
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