Phplr
A test that measures the acidity level of fluid around the lungs to help diagnose the cause of fluid buildup.
{"Pleural fluid pH measures how acidic the fluid around your lungs is","Normal pH is around 7.60-7.65; low pH (<7.2) indicates infection or complication","The test helps doctors decide if you need chest tube drainage","Sample is collected via thoracentesis (needle procedure)","Results guide treatment decisions for lung conditions"}
Key facts at a glance
- LOINC
- 2750-8
- Short code
- pH-PF
- Synonyms
- pH Plr
- Category
- chemistry
- Sample
- serum
- Container
- Sterile container, heparinized syringe, or lavender top (EDTA) tube
- Units
- not specified
- Ref low
- 7.6
- Ref high
- 7.64
- Critical range
- 7.2 not specified – —
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 18 years
- Method
- pH electrode or blood gas analyzer
- CPT
- 86153
- SNOMED
- 389110006
- Specimen volume
- 1-2 mL
- Stability
- Analyze immediately; stable for up to 1 hour on ice
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 1–2 hours
- Order
- routine
What is this test?
The pleural fluid pH test measures the acidity level (pH) of fluid that has collected in the pleural space—the area between your lungs and chest wall. This test is part of a broader pleural fluid analysis that helps doctors understand why fluid is accumulating and how to treat it.
How is the sample collected?
A doctor will perform a procedure called thoracentesis. You will sit upright and lean forward on a table. After numbing the area, the doctor inserts a thin needle between your ribs to withdraw fluid from the pleural space. The procedure usually takes 15-30 minutes. You may feel pressure or discomfort during the needle insertion.
What do the results mean?
Normal pleural fluid pH ranges from approximately 7.60 to 7.65, which is slightly more alkaline than blood. When pH falls below 7.2, it typically indicates a complicated situation that often requires intervention, such as chest tube drainage. Specific interpretations include: • pH > 7.60: Normal; fluid is likely a simple effusion • pH 7.30-7.60: May indicate heart failure or other causes • pH < 7.2: Suggests complicated parapneumonic effusion, empyema, or malignant effusion
Are there any risks?
Thoracentesis is generally safe, but potential risks include pneumothorax (lung puncture causing air leak), bleeding, infection, or discomfort at the puncture site. These complications are uncommon. Your doctor will monitor you after the procedure.
Reference range
7.60-7.64not specified
No special patient preparation. Collect anaerobically in heparinized syringe and analyze immediately.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Frequently asked questions
Why is pleural fluid pH tested instead of blood pH?
Do I need to fast before this test?
How long does it take to get results?
What happens if my pH is low?
Sources
- 1
- 2
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy