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- Body Fluid pH
Special Instructions
Specify body fluid source on the request form.
This test is not appropriate for measurement of pleural fluid pH. Due to sample instability and a requirement to transport the specimen, that measurement should be made locally using a blood gas analyzer.
Expected Turnaround Time
2 - 4 days
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.
Specimen Requirements
Specimen
Serous fluids (pericardial, ascitic) or synovial fluid
Volume
5 mL
Minimum Volume
1 mL
Container
Sample should be collected anaerobically. A lithium heparin tube to prevent clotting should be used, especially if the syringe has not been rinsed with heparin.
Collection
A syringe rinsed with 0.2 mL heparin, 1:1000 may be used; collect anaerobically. If the specimen is collected in a syringe, all air should be expelled and the needle sealed and capped.
Storage Instructions
Room temperature
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 14 days |
Refrigerated | 14 days |
Frozen | 14 days |
Freeze/thaw cycles | Stable x3 |
Causes for Rejection
Pleural fluid, spinal fluid (CSF), urine, feces or blood specimen received; icteric samples
Test Details
Use
This test is used to determine pH of body fluid.
Limitations
This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.
Methodology
Electrochemical (pH meter)
Reference Interval
Not established
Additional Information
pH >7.3 is in general a feature of transudates. Low pH and low glucose together are found with loculated effusion or with empyema.1 Effusions related to lupus erythematosus generally have a pH >7.35.2
Effusions of tuberculosis usually have pH <7.3,2 usually with increased lymphocytes.
In bacterial peritonitis pH is decreased: cutoff <7.35 is useful, especially with PMNs >500/mm.1 The mean pH of infected ascitic fluid is reported as 7.24. The arterial-ascitic fluid pH gradient >0.10 with >500 PMNs is described as virtually diagnostic of bacterial peritonitis.3
Reduction of pH and in some, but not all, series increments of PMN counts may be found also with peritoneal metastases.3,4
Footnotes
1. Potts DE, Taryle DA, Sahn SA. The glucose-pH relationship in parapneumonic effusions. Arch Intern Med. 1978 Sep;138(9):1378-1380.28707
2. Kjeldsberg CR, Knight JA. Body fluids: Laboratory examination of cerebrospinal, synovial, and serous fluids: a textbook atlas. American Society of Clinical Pathologists Press, Chicago, IL; 1982.
3. Garcia-Tsao G, Conn HO, Lerner E. The diagnosis of bacterial peritonitis: Comparison of pH, lactate concentration and leukocyte count. Hepatology. 1985 Jan-Feb;5(1):91-96.3967868
4. Sahn SA, Good JT. Pleural fluid pH in malignant effusions: Diagnostic, prognostic and therapeutic implications. Ann Intern Med. 1988 Mar;108(3):345-349.3341671
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 011254 | pH, Body Fluid | 2748-2 | 011254 | pH, Body Fluid | 2748-2 |
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