What are the biochemical parameters of pleural fluid that best identify parapneumonic effusions?

LDH/ADA ratio in pleural fluid for the diagnosis of infectious pleurisy

Pleural effusion (PE) is a common medical concern, often requiring thoracentesis for a definitive diagnosis. An elevated pleural fluid adenosine deaminase (ADA) may indicate tuberculosis, but this is not always the case. This study aimed to evaluate the accuracy of biomarkers determined in pleural fluid and propose a new diagnostic strategy for PE in patients with high levels of ADA in pleural fluid. This retrospective analysis studied patients with PE who received thoracentesis for the first time with an ADA level of > 33 U/L in the pleural fluid analysis at two tertiary hospitals from March 2019 to March 2023. Demographic and clinical data, as well as pleural fluid biomarkers and their ratios, were studied and compared between different PE groups, and a decision tree was developed. During the study period, 259 patients were enrolled, with four different types of PE: parapneumonic (PPE) 155, tuberculosis (TPE) 41, malignant (MPE) 50, and miscellaneous 13. Biomarkers and their ratios performed well in the differential diagnosis of PE, with the LDH/ADA ratio distinguishing between PPE and non-PPE with sensitivity and specificity of 98.06% and 98.08%, respectively. The combination of LDH/ADA ratio, ADA, and mononuclear cell percentage was identified as important factors for creating a decision tree with an overall accuracy of 89.96%. The pleural fluid LDH/ADA ratio was a useful diagnostic for distinguishing PPE from non-PPE, and a decision tree with an accuracy of 89.96% was created to differentiate the four forms of PE in clinical situations.

Diagnosis of parapneumonic pleural effusion with serum and pleural fluid Activin A

OBJECTIVE

The aim is to evaluate the diagnostic value of Activin A levels in serum and pleural fluid on Parapneumonic Pleural Effusion (PPE).

METHODS

The authors collected serum and pleural fluid from 86 PPE and 37 Non-PPE (NPPE) patients. Including Activin A, levels of biomarkers such as Lactate Dehydrogenase (LDH), Procalcitonin (PCT), and C-Reactive Protein (CRP) were measured. All factors were calculated for association with days after admission. The diagnostic potential of biomarkers on PPE was considered by Receiver Operating Characteristic (ROC) curve analysis.

RESULTS

Levels of Activin A in serum and pleural fluid of PPE patients were significantly higher than those of the NPPE patients. Moreover, concentrations of Activin A in pleural fluid showed a more obvious relevant days after admission. ROC curve analysis found that Activin A in pleural fluid had AUCs of 0.899 with 93% sensitivity and 84% specificity for PPE diagnosis.

CONCLUSION

Activin A in pleural fluid correlated with disease severity could act to diagnose PPE.

Combined analysis of C-reactive protein in pleural fluid and serum is effective in the differential diagnosis of exudative pleural effusions

Background

Exudative pleural effusion (EPE) is one of the common pleural manifestations of various diseases. Differential diagnosis of EPE is imperative clinically as it identifies different causes of EPE, thereby, enabling effective treatments. Thoracoscopy is a useful tool for differential diagnosis of EPE; however, some patients refuse thoracoscopic examination due to its invasive nature. In addition, the specificity and sensitivity of existing routine tests of EPE are unsatisfactory. Therefore, there is a great need to establish an effective method for the differential diagnosis of EPE.

Methods

This study was a single-institution retrospective analysis of diagnostic efficiency of C-reactive protein (CRP) and procalcitonin (PCT) between March 2018 and September 2018. A total of 87 patients diagnosed with EPE were enrolled. All participants underwent diagnostic thoracentesis. The EPE was examined using biochemical, routine, microbiological, and cytological methods. Pathological cytology detection was necessary for those suspected of malignant PE. Benign PE originates in patients with pneumonia, empyema, and tuberculosis. The levels of CRP and PCT in EPE and serum were measured before treatment. Correlation analysis and receiver-operating characteristic (ROC) curve analysis were conducted to determine the underlying relationship between levels of CRP and PCT, and for differential diagnosis.

Results

The ROC analysis showed that the sensitivity and specificity for the analysis of pleural fluid CRP (p-CRP) were higher (cut-off: 17.55 pg/mL; sensitivity: 75.00%, specificity: 83.90%) than that of serum CRP (s-CRP, cut-off: 23.90 pg/mL; sensitivity: 71.00%, specificity: 80.4%) in the differential diagnosis for EPE. However, the analysis of pleural fluid PCT (p-PCT) and serum PCT (s-PCT) did not demonstrate correlations with EPE. Combined analysis of p-CRP (cut-off: 17.55 mg/dL) with s-CRP (cut-off: 23.9 pg/mL) showed the highest diagnostic accuracy (88.4%) in diagnosing infectious EPE.

Conclusions

The data support the close relationship between combined analysis of p-CRP with s-CRP and effective and accurate differential diagnosis of EPE, due to its higher sensitivity and specificity. However, as a highly sensitive marker for diagnosing bacterial infections, neither s-PCT nor p-PCT, showed correlations with the differential diagnosis of EPE.

Diagnosis of Parapneumonia Pleural Effusion with Serum and Pleural Fluid Cell-Free DNA

Objective

As cell-free DNA levels in the pleural fluid and serum of parapneumonic pleural effusion (PPE) patients have not been thoroughly explored, we evaluated their diagnostic potential.

Methods

Twenty-two PPE and 16 non-PPE patients were evaluated. Serum and pleural fluids were collected, and cell-free DNA was quantified. All biomarkers were assessed for correlation with days after admission. Receiver operating characteristic (ROC) curve analysis was used to determine diagnostic accuracy and optimal cut-off point.

Results

Nuclear and mitochondrial DNA levels in the pleural fluid and nuclear DNA levels in serum of PPE patients were significantly higher than in those of the non-PPE patients. However, only cell-free DNA levels in pleural fluid correlated with days after admission among PPE patients (r= 0.464, 0.538, respectively). ROC curve analysis showed that nuclear and mitochondrial DNA in pleural fluid had AUCs of 0.945 and 0.889, respectively. With cut-off values of 134.9 and 17.8 ng/ml for nuclear and mitochondrial DNA in pleural fluid, respectively, 96% sensitivity and 81% specificity were observed for PPE diagnosis.

Conclusion

Nuclear and mitochondrial DNA in pleural fluid possess PPE diagnostic potential and correlated with disease severity. Serum nuclear DNA could also be used to distinguish freshly admitted PPE patients (Day 1) from non-PPE patients, but with less accuracy.

Performance of procalcitonin in diagnosing parapneumonic pleural effusions: A clinical study and meta-analysis

BACKGROUND

Parapneumonic pleural effusion (PPE) is a common complication of pneumonia. The accurate diagnosis of PPE remains a challenge. Recent studies suggest that procalcitonin (PCT) emerges as a potential biomarker for PPE. Our study aimed to determine the diagnostic value of PCT for PPE by a clinical study and summarize the overall diagnostic performance of PCT through a meta-analysis.

METHODS

Demographic and clinical data of the patients with PPE and controls were collected in our clinical study. The diagnostic performances of serum PCT (s-PCT) were analyzed via receiver operating characteristic (ROC) curve analysis, using area under the curve (AUC) as a measure of accuracy. Literature databases were systematically searched for the studies examining the accuracy of PCT for diagnosing PPE. Data on sensitivity, specificity, positive/negative likelihood ratio (PLR/NLR), and diagnostic odds ratio (DOR) were pooled. Summary ROC curves and AUC were used to evaluate overall test performance.

RESULTS

In our clinical study, 47 patients with PPE and 101 controls were included. The s-PCT levels were significantly increased in the setting of PPE (5.44 ± 9.82 ng/mL) compared with malignant PE (0.15 ± 0.19 ng/mL), tuberculous PE (0.18 ± 0.16 ng/mL), and transudates (0.09 ± 0.03 ng/mL) (P < .001). Using a cutoff value of 0.195 ng/mL, the sensitivity and specificity of s-PCT in diagnosing PPE were 0.83 and 0.80, respectively, and AUC was 0.89. In addition, 11 studies were included in our meta-analysis. Summary performance estimates for s-PCT in diagnosing PPE were as follows: sensitivity, 0.78 (95% CI: 0.71-0.84); specificity, 0.74 (95% CI: 0.69-0.78); PLR, 3.46 (95% CI: 2.09-5.74); NLR, 0.27 (95% CI: 0.14-0.54); DOR, 12.37 (95% CI: 4.34-41.17); and AUC, 0.84. The corresponding estimates for p-PCT were as follows: sensitivity, 0.62 (95% CI: 0.57-0.67); specificity, 0.71 (95% CI: 0.68-0.75); PLR 2.31 (95% CI: 1.81-2.95); NLR, 0.47 (95% CI: 0.35-0.63); DOR, 5.48 (95% CI: 3.07-9.77); and AUC, 0.80.

CONCLUSION

Both s-PCT and p-PCT might have modest performance in diagnosing PPE. However, more studies on a large scale should be performed to confirm our findings.

Recognizing and differentiating uncommon body fluids: Considerations and tools for a proper practical approach

Clinical laboratories are regularly requested to inspect uncommon body fluids obtained from patients because clinicians are uncertain as to the origin of the collected material. They may need this information for the actual diagnosis, to confirm a supposition, or for guiding treatment and invasive operations like draining and puncturing. Often there is also a need to know more precisely what is going on in the cavity that gave rise to the fluid, for instance a local infection or metastasis, or whether the cavity is connected to organs or fluid compartments nearby etcetera. The results of the laboratory investigations often have () direct consequences. As the investigation of uncommon body fluids is distinct from routine laboratory analyses it requires special attention. This paper presents an overview of the characteristics of uncommon human body fluids, constituents useful as markers for recognizing and differentiating fluids and considerations that have to be taken into account when interpreting the results of analyses. In addition a number of practical recommendations for approaching the task of identifying uncommon body fluids are given.

Pleural fluid cell-free DNA in parapneumonic pleural effusion

OBJECTIVES

To measure the accuracy of pleural fluid cell-free DNA (cfDNA) concentration for diagnosis of parapneumonic pleural effusions (PPE).

DESIGN AND METHODS

We studied pleural fluids obtained by thoracocentesis in patients with pleural effusion. DNA was automatically extracted from pleural fluid using the MagNa Pure Compact instrument (Roche Diagnostics), and was measured by a real-time quantitative PCR assay for the β-globin gene using a Light-Cycler 480 Real-Time PCR instrument (Roche Diagnostics). Patients were classified into two groups according to the etiology of pleural effusion: PPE and NOT PPE. The diagnostic accuracy was determined using receiver operating characteristic (ROC) techniques by analyzing the area under the ROC curve (AUC).

RESULTS

We studied 78 patients with ages between 1 and 86 years old (median=64). Sixteen patients were PPE and 62 were NOT PPE (24 transudative, 30 malignant and 8 other etiology). Pleural fluid cfDNA concentration was higher in patients with PPE (median=46,240 ng/mL) than in those with NOT PPE (median=224 ng/mL). The AUC value was 0.907 (p<0.0001) and the optimal cut-off value was 6740 ng/mL exhibiting 87.5% sensitivity and 80.6% specificity. Also, there were significant differences between transudative and exudative effusions according to pleural fluid cfDNA concentration (p<0.0001). The AUC value was 0.994 and the optimal cut-off value was 162ng/mL exhibiting 100% sensitivity and 96.3% specificity.

CONCLUSIONS

Pleural fluid cfDNA concentration showed high accuracy for diagnosis of PPE and to discriminate between transudative and exudative effusions.

Homocysteine: new tumor marker in pleural fluid

There are no published studies examining the utility of total homocysteine (HCY) in pleural fluid. The aim was to measure the accuracy of pleural fluid HCY concentration for diagnosis of malignant pleural effusion (MPE). We studied pleural fluids obtained by thoracocentesis in patients with pleural effusion. Pleural fluid HCY concentration was measured by immunonephelometry using N Latex HCY reagent with monoclonal antibody in automated analyzers BNII (Siemens Diagnostics®). Patients were classified into two groups according to the etiology of pleural effusion: benign pleural effusions (BPE) and MPE. Pleural effusion was categorized as MPE if malignant cells were demonstrated in pleural fluid or pleural biopsy. The accuracy of pleural fluid HCY concentration for diagnosis of MPE was determined using receiver operating characteristic (ROC) techniques by analyzing the area under the ROC curve (AUC). We studied 89 patients with ages between 1 and 96 years old (median = 66). Forty-eight patients were BPE and 41 were MPE. Pleural fluid HCY concentration was significantly higher in patients with MPE (median = 13.70 μmol/L) than in those with BPE (median = 8.05 μmol/L). The AUC value was 0.833 (95 % confidence interval (CI) 0.739-0.903). The optimal cutoff value was 13.1 μmol/L exhibiting 56.1 % (95 % CI 39.8-71.5) sensitivity and 85.4 % (95 % CI 72.2-93.9) specificity. Pleural fluid HCY concentration showed high diagnostic accuracy to predict whether a pleural effusion is benign or malignant. Pleural fluid HCY concentration may be measured easily and quickly in automated analyzers and could be a tumor marker commonly used for diagnosis of MPE.

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.