Effects of coexisting pneumonia and end-stage renal disease on pleural fluid analysis in patients with hydrostatic pleural effusion.

BACKGROUND In individual patients, especially those who are hospitalized, several conditions often coexist that may be responsible for the development of a pleural effusion and may affect the pleural fluid analysis (PFA). The objective of this study was to investigate the effects of end-stage renal disease and pneumonia on PFA in patients with hydrostatic pleural effusion. METHODS In a retrospective analysis of 1,064 consecutive patients who underwent thoracentesis at a university hospital, cell counts and pleural fluid protein, lactate dehydrogenase, pH, and glucose levels were examined in those (n = 300) with clinical evidence of hydrostatic pleural effusion. RESULTS The 300 patients (28.1%) with pleural effusions had congestive heart failure (CHF), circulatory overload (CO), or both. Expert consensus was achieved in 66 (22%) for CHF as the sole diagnosis (SCHF), 30 (10%) for CHF and coexisting pneumonia (PCHF), and 26 (8.7%) for end-stage renal disease (ESRD) with coexisting CO or CHF. The remaining 178 patients were excluded because of complicating conditions. There were minor, but statistically significant differences in pleural fluid/serum protein ratios in patients with ESRD with coexisting CO or CHF compared with SCHF. Compared with SCHF, there were statistically significant tendencies for higher protein and lactate dehydrogenase concentrations and lower pH levels in those with PCHF. The total nucleated cell count and the absolute neutrophil count were significantly higher in PCHF. CONCLUSIONS ESRD in patients with hydrostatic pleural effusions has a minimal effect on the PFA. Coexisting pneumonia most often results in an exudative effusion in patients with CHF.