11/13/24, 7\:33 PM Guide | Pleural fluid interpretation
Pleural
Table of contents
Introduction
This guide provides a structured approach to the interpretation of pleural
vary between labs, so always consult your local medical school or hospital guidelines.
A pleural e
rays can detect a pleural e
Once the accumulated
percussion and diminished breath sounds on the a
tracheal deviation may occur away from the e
the size and location of a pleural e
Normal pleural
Typical
Appearance\: clear
pH\: 7.60-7.64
Protein\: \< 2% (1-2 g/dL)
White blood cells (WBC)\: \< 1000/mm³
Glucose\: similar to that of plasma
LDH\: \<50% plasma concentration
Amylase\: 30-110 U/L
Triglycerides\: \<2 mmol/l
Cholesterol\: 3.5–6.5 mmol/l
Transudate vs exudate
Transudate
Transudative pleural e
permeability, and oncotic pressure.
Conditions associated with transudative pleural e
Congestive heart failure
Liver cirrhosis
Severe hypoalbuminemia
Nephrotic syndrome
Exudate
pleural
Exudative pleural e
Conditions associated with exudative pleural e
Malignancy
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Infection (e.g. empyema due to bacterial pneumonia)
Trauma
Pulmonary infarction
Pulmonary embolism
Diagnostic criteria for pleural e
Transudate
Protein \<30 g/L (in patients with a normal serum protein level)
Exudate
Protein >30 g/L (in patients with a normal serum protein level)
Light's criteria
Light’s criteria are more accurate for the diagnosis of exudative e
The
The ratio of pleural
The ratio of pleural
The pleural
If a patient is thought to have a transudative pleural e
protein gradient should be examined.
Colour
Frankly purulent
A milky
malignancy, chronic in
Grossly bloody
ruptured aortic aneurysm and malignancy.
Straw-coloured
The presence of food particles suggests oesophageal rupture.
Black pleural
Aspergillus niger infection
Malignant melanoma (black colour caused by cells containing melanin pigment)
Haemorrhage and haemolysis associated with non-small cell lung cancer
Pleural
Levels greater than 1000 IU/L are suggestive of empyema, malignancy or rheumatoid e
Glucose
A low pleural
associated with TB, malignancy and oesophageal rupture.
A very low pleural glucose concentration (\<1.6 mmol/l) is indicative of empyema and rheumatoid disease.
Pleural pH
A pleural
In malignant e
shorter life expectancies.
Amylase
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Pleural
White blood cells (WBC)
Results generally are not diagnostic, but most transudates have WBC counts less than 1000 cells/µL, whereas exudates
generally have WBC counts greater than 50,000 cells/µL.
Pleural
Neutrophil dominant e
Pleural
Blood in the pleural space may be the result of pulmonary embolism or benign asbestosis. The presence of PFE does not
exclude malignancy.
Cholesterol and triglycerides
Pleural
chylothorax.
A triglyceride level of less than 0.56 mmol/l with a cholesterol level of greater than 5.18 mmol/l is associated with
pseudochylothorax.
Worked examples
Case 1
A 52-year-old male presents with a cough, shortness of breath and fever. CXR shows a right-sided pleural e
thoracentesis is performed and the results of the pleural
Colour\: purulent
Pleural/serum total protein ratio\: >0.5
pH\: 7.1
WBC count\: 67,000 cells/µL
Glucose\: 1.5 mmol/l
LDH\: 1430 IU/L
The most likely diagnosis is empyema. This gentleman has presented with, fever, shortness of breath and cough. The pleural
Case 2
A 56 -year-old, previously well woman was admitted with a 4-week history of a cough, night sweats and 1-week history of
progressive breathlessness. She had never smoked and has no history of heart disease or rheumatological disease. Pleural
Colour\: milky-white, odourless
Triglyceride\: 0.5 mmol/l
Cholesterol\: 12.4 mmol/l
The most likely diagnosis is pseudochylothorax. This woman has presented with a cough, night sweats and progressive
breathlessness. A triglyceride level of less than 0.56 mmol/l and a cholesterol level of more than 5.18 mmol/l is indicative of
pseudochylothorax. A pleural biopsy revealed chronic in
References
1. Light RW, Macgregor MI, Luchsinger PC, Ball WC Jr. Pleural e
Ann Intern Med1972;77\:507-13.
2. Pettersson T, Riska H. Diagnostic value of total and di
1981;210\:129–35. (3)
3. Saraya T; Light RW; Takizawa H; Goto H, Black pleural e
https\://app.geekymedics.com/osce-guides/data-interpretation/pleural-fluid-interpretation/ 3/411/13/24, 7\:33 PM Guide | Pleural fluid interpretation
4. Sahn S. Pleural
5. Good JT Jr., Taryle DA, Maulitz RM, et al. The diagnostic value of pleural
6. Light RW, Ball WC. Glucose and amylase in pleural e
7. Villena V, Lopez-Encuentra A, Garcia-Lujan R, et al. Clinical implications of the appearance of pleural
thoracentesis. Chest 2004;125\:156–9. (3).
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