Days Set Up
Daily, 24 hours, 7 days a week (including holidays)
Analytic Time

1 - 4 hrs

MiChart Code
Soft Order Code

Test Updated:


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Find a Requisition

All specimens should be accompanied by a requisition.

Submitting Specimens

Learn about how to properly label and where to ship specimens.

Order Kits and Supplies

MLabs provides all the supplies necessary for the collection of specimens.

Test FAQ

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Test Overview

Test Methodology

Blood gas analyzer (electrode based method)

Test Usage

Pleural fluid pH is a key component in the diagnosis of pleural infections (including tuberculosis), rheumatoid pleural effusion, and esophageal rupture, as well as management of patients with pleural effusions. A low pleural fluid pH is associated with high metabolic activity in the pleural space, and provides supportive evidence for pleural infections. Additionally, in malignant pleural effusions, low pleural fluid pH correlates with a poor prognosis.

Reference Range

pH > or = 7.3

Note: Analytical measurement range for the pH using the blood gas analyzer (electrode based method) is 6.7-7.8 . pH results >7.8 will be reported as ".7.8", and are within the reference range.

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Specimen Requirements

Collection Offsite

Collect pleural fluid in blood gas syringe, clean plastic container or red top tube with no preservatives. Deliver to laboratory immediately after collection. Delays in the delivery of the specimen to the laboratory, and/or delayed analysis may significantly increase the pH.

Red Top Tube
Normal Volume
0.5 mL
Minimum Volume
0.3 mL

Billing Information

CPT Code
Pro Fee Code

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Our High Standard

Quality that sets us apart

As the reference laboratory division of Michigan Medicine's Department of Pathology, MLabs shares the institution's commitment to applying established quality principles to clinical laboratory testing. Like other large organizations in complex, consequential fields, we rely on an established approach to monitor quality throughout the testing process.