Soluble leukocyte selectin in the analysis of pleural effusions.

STUDY OBJECTIVES To determine if soluble leukocyte selectin (sL-selectin) levels in serum and pleural fluid (PF) are an inflammatory marker that differentiates pleural effusion transudates from exudates. DESIGN sL-selectin PF and serum levels were measured in consecutive patients and compared to established criteria. SETTING A tertiary-care military medical center. PATIENTS One hundred twenty patients undergoing diagnostic or therapeutic thoracentesis. INTERVENTIONS PF and serum samples were collected during thoracentesis and analyzed separately for sL-selectin levels. Results were compared with clinical diagnosis and established PF criteria including the criteria of Light et al, cholesterol ratio, total bilirubin ratio, and albumin gradient. MEASUREMENTS AND RESULTS sL-selectin levels in PF and serum were determined in 109 patients. By clinical diagnosis, mean +/- SD PF sL-selectin levels were 200.2 +/- 124.3 ng/mL in transudates and 496.8 +/- 379.2 ng/mL in exudates (p < 0.001). By the criteria of Light et al, mean PF sL-selectin levels were 195.7 +/- 105.2 ng/mL in transudates and 448.2 +/- 367.6 ng/mL in exudates (p < 0.001). Mean sL-selectin PF to serum ratios were 0.31 +/- 0.17 in transudates and 0.72 +/- 0.31 in exudates (p < 0.001) by clinical criteria, and 0.31 +/- 0.18 in transudates and 0.64 +/- 0.33 in exudates (p < 0.001) by the criteria of Light et al. No significant difference was noted with serum sL-selectin levels between groups. CONCLUSIONS sL-selectin is an inflammatory marker that differentiates transudates from exudates in pleural effusions and is a sensitive indicator for PF analysis.