Pleural Effusion-Glucose and pH Patterns

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]

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]]

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]])

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]])

References

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