General Concepts

• In general low pleural glucose correlates with low pleural pH
  [Potts DE, Willcox MA, Good JTJ, et al: The acidosis of low-glucose pleural effusions. Am Rev Respir Dis 1978; 117:665-671]

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Low Pleural pH

Physiology of Low Pleural pH

• Low pH is related to the accumulation of lactic acid and CO2 in pleural fluid

Etiology

• Complicated Parapneumonic Effusion/Empyema (see [[Pleural Effusion-Parapneumonic]])
• Rheumatoid Arthritis (see [[Rheumatoid Arthritis]]): 70-80% of cases have glucose <30 mg/dL
• [[SLE]]: only 20% of cases have pH <7.3 and glucose <60
• Malignancy ([[Pleural Metastases]], [[Mesothelioma]], etc)
  • Presence of low glucose correlates with positive pleural cytology
  • Presence of low glucose correlates with positive pleural cytology
• [[Paragonimiasis]]: typically low pH, low glucose, high LDH, and with pleural eosinophilia
• [[Churg-Strauss Syndrome]]: typically low pH, low glucose, high LDH, and with pleural eosinophilia
• Tuberculosis (see [[Tuberculosis]]
• Hemothorax (see [[Pleural Effusion-Hemothorax]])
• [[Esophageal Perforation]]
• Systemic Metabolic Acidosis (see [[Metabolic Acidosis-Elevated Anion Gap]] and [[Metabolic Acidosis-Normal Anion Gap]])
• Urinothorax (see [[Pleural Effusion-Urinothorax]]

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Low Pleural Glucose (<60 mg/dL)

Physiology of Low Pleural Glucose

• Low pleural glucose indicates
  • Thickened pleura, impairing glucose diffusion into pleural space
  • Increased glucose metabolism in pleural space

Etiology of Low Pleural Glucose

• Complicated Parapneumonic Effusion/Empyema (see [[Pleural Effusion-Parapneumonic]])
• Rheumatoid Arthritis (see [[Rheumatoid Arthritis]]): 70-80% of cases have glucose <30 mg/dL
• [[SLE]]: only 20% of cases have pH <7.3 and glucose <60
• Malignancy ([[Pleural Metastases]], [[Mesothelioma]], etc)
  • Presence of low glucose correlates with positive pleural cytology
  • Presence of low glucose correlates with positive pleural cytology
• [[Paragonimiasis]]: typically low pH, low glucose, high LDH, and with pleural eosinophilia
• [[Churg-Strauss Syndrome]]: typically low pH, low glucose, high LDH, and with pleural eosinophilia
• Tuberculosis (see [[Tuberculosis]]
• Hemothorax (see [[Pleural Effusion-Hemothorax]])

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Low Pleural pH+Low Glucose

Etiology of Low Pleural pH + Low Pleural Glucose

• Complicated Parapneumonic Effusion/Empyema (see [[Pleural Effusion-Parapneumonic]])
• [[Rheumatoid Arthritis]]: 70-80% of cases have glucose <30 mg/dL
• [[SLE]]: only 20% of cases have pH <7.3 and glucose <60
• Malignancy ([[Pleural Metastases]], [[Mesothelioma]], etc)
  • Presence of low glucose correlates with positive pleural cytology
  • Presence of low glucose correlates with positive pleural cytology
• [[Paragonimiasis]]: typically low pH, low glucose, high LDH, and with pleural eosinophilia
• [[Churg-Strauss Syndrome]]: typically low pH, low glucose, high LDH, and with pleural eosinophilia
• Tuberculosis (see [[Tuberculosis]]
• Hemothorax (see [[Pleural Effusion-Hemothorax]])

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References

• Potts DE, Willcox MA, Good JTJ, et al: The acidosis of low-glucose pleural effusions. Am Rev Respir Dis 1978; 117:665-671