Lysozyme (muramidase) in pleural effusions and serum

Area of Science:

• Pulmonology
• Infectious Diseases
• Biochemistry

Background:

• Pleurisy diagnosis can be challenging, requiring differentiation between infectious, malignant, and cardiac causes.
• Lysozyme, an enzyme involved in immune response, has been investigated as a potential biomarker in various conditions.

Purpose of the Study:

• To evaluate the diagnostic utility of paired pleural fluid and serum lysozyme levels in differentiating various types of pleurisies.
• To determine if the pleural fluid to serum lysozyme ratio can effectively identify tuberculous pleurisy.

Main Methods:

• Analysis of pleural fluid and serum lysozyme activity in 118 patients with different causes of pleurisy.
• Comparison of lysozyme levels between tuberculous effusions and those caused by malignancy or heart failure.
• Calculation and evaluation of the pleural fluid to serum lysozyme ratio.

Main Results:

• Tuberculous effusions exhibited significantly higher lysozyme activity compared to effusions from malignancy or heart failure (P < 0.001).
• A pleural fluid to serum lysozyme ratio of 1.0 or greater was observed in all patients with confirmed or suspected tuberculous pleurisy.
• Only three patients with non-tuberculous conditions (malignancy, lupus erythematosus, sarcoidosis) exceeded this ratio.

Conclusions:

• The pleural fluid to serum lysozyme ratio is a valuable tool for the differential diagnosis of tuberculous pleurisy.
• This ratio demonstrates high sensitivity and specificity in identifying tuberculous effusions, aiding clinical decision-making.