pH, Pleural Fluid

pH, Pleural Fluid

Alternate Test Name

Pleural Fluid pH

Mnemonic

LAB3173
PFLPH

Category

Chemistry

Methodology

ISE by Blood Gas Analyzer

Test Performance Schedule

Sunday - Saturday

Result Availability

Within 24 hours – STAT upon request

Container

Green top (lithium heparin) tube or Container with tightly fitting lid (anaerobic storage)

Volume

Pref. Vol.: 3.0 mL
Min. Vol.: 1.5 mL

Collection Instructions

• Document source of body fluid on label and requisition
• Immediately transport to laboratory
• Pleural fluid should be handled and stored anaerobically

Transportation Instructions

Refrigerated or on ice

Remarks

Ensure that samples are free of particulate matter and bubbles

CPT Codes

83986

Effective/Revised

11/10/15

Excess fluid in the pleura is identified as a pleural effusion. A pleural effusion is classified as either transudative or exudative. Transudative pleural effusions result from an imbalance in hydrostatic and oncotic pressure in the normal production of pleural fluid. Exudative pleural effusions result from changes within the pleura, such as lymphatic blockage or increased capillary permeability. These changes are often caused by infectious, inflammatory, or neoplastic processes that do not originate in the pleura.

The pleural fluid pH measurement provides important information for the diagnosis of exudative pleural effusions. Pleural fluid should be tested using a blood gas analyzer at 37°C. Guidelines for pleural fluid have been established by the American Thoracic Society.

Interpretation:

pH 7.40-7.55: Most likely transudative effusion

pH <7.30: Often associated with rheumatoid pleurisy, empyema, or possible malignant effusion (correlation with cytopathology and neutrophilic count is advised for patient management)

pH 7.10-7.20: Most likely complicated parapneumonic effusion (correlation with glucose level, neutrophilic count is advised). Consider drainage for resolution.