Abstract Background/Rationale Paraneumonic effusions are pleural fluid accumulations secondary to pulmonary infection, characterized by inflammatory biochemical changes and radiologic alterations. Recent studies suggest that computed-tomography (CT) attenuation, expressed in Hounsfield units (HU), may differentiate exudative from transudative effusions. This study evaluated the relationship between pleural fluid LDH, CT-derived radiodensity, exudate status, and paraneumonic effusions in a minority low-income community. Then, we compared our results with those of prior multicenter imaging analyses. Methods We conducted a retrospective study at Wyckoff Heights Medical Center, located in Brooklyn, NY. Patients who underwent thoracentesis from January 2022 through December 2024 with pre-procedure CT chest and complete fluid/serum studies. Variables included HU Average, pleural fluid LDH, exudate status according to Light’s criteria, and parapneumonic status according to clinical presentation. Group comparisons were performed with t-tests and Fisher’s tests, and correlations with Pearson’s and Spearman’s coefficients. Regression analysis of paraneumonic effusion as the dependent variable and HU Average, LDH, and exudate classification as predictors was completed. Results From 155 patients, 123 met our inclusion criteria. Our cohort was predominantly older adults (mean ≈ 67 years), 55% female, and mainly Black/African American (45%), White (28%), Hispanic (15%), Asian (7%), and other ethnicities (5%). 60% were current/former smokers. Both HU Average (p = 0.0001) and pleural fluid LDH (p 0.001) were significantly higher among exudative effusions, and a positive correlation (r ≈ 0.4, p = 0.0027) was found between HU and LDH. Exudate status correlated significantly with paraneumonic effusion (p 0.05). In multivariable analysis, LDH and exudate status were independent predictors of paraneumonic effusion, while HU Average showed a positive trend. These findings parallel those of Yalçin-Şafak et al. (2017), who reported mean HU ≈ 8.8 for exudates versus 2.9 for transudates (cut-off ≥ 5 HU, specificity 70%). Similarly, Zhang et al. (2024) validated CT-derived HU as a diagnostic tool, identifying a threshold of 10.8 HU (specificity 68.9%) and confirming a strong correlation between HU and pleural fluid protein/LDH ratios. The concordance of our findings with these large-scale analyses reinforces the diagnostic value of radiodensity for pleural effusion analysis. Conclusions Our study demonstrates that higher HU values are characteristic of exudative and paraneumonic effusions, reflecting the inflammatory nature. The integration of radiologic HU quantification with biochemical markers aligns with prior multicenter evidence and supports a non-invasive adjunct to Light’s criteria. This combined approach can improve early stratification of infectious pleural disease and reduce reliance on invasive thoracentesis. This abstract is funded by: none
Martinez et al. (Fri,) studied this question.