Pleural fluid biochemistry

Alternative names, keywords

Light's criteria, transudate vs. exudate.

Samples required

● Plain pleural fluid (gold cap, 5 mL tube) for protein, LDH, cholesterol

● Fluoride oxalate-preserved pleural fluid (grey cap, 2 mL tube) for glucose.

Smaller tubes are available for paediatric samples.

Samples must be received in Vacuette^® evacuated sample tubes. This is safer for you, safer for the lab, and more efficient for the lab.

Test indications

Differentiating transudate from exudate.

Test information

_{Please note this test is not currently UKAS accredited.}

Factors affecting test performance/ results

See serum protein, serum LDH, serum cholesterol and plasma glucose for method-specific information on potential interferences. Note that the tests have not been validated for use in pleural fluids.

Results should always be assessed in conjunction with the patient’s medical history, clinical examination and other findings.

Reference range

High likelihood of sample being exudate if ANY of the following criteria are satisfied:

    Pleural fluid: serum protein ratio > 0.5
    Pleural fluid: serum LDH ratio > 0.6
    Pleural fluid cholesterol > 1.55 mmol/L

_{No pleural fluid LDH reference range available for new LDH method in use December 2020.}

Turnaround time

Same day (within 1h if urgent)

Enquiries

Biochemistry (Automation)