Differentiating transudative from exudative pleural effusion: should we measure effusion cholesterol dehydrogenase?

Diagnostic value of pleural cholesterol in differentiating exudative and transudative pleural effusion

Background

Pleural effusions are most commonly classified as transudative or exudative based on Light's criteria which has shown misclassification in 10%–20% of cases. Studies have demonstrated lesser misclassification with pleural fluid cholesterol criteria. Thus, this study aimed to find the diagnostic properties of pleural fluid cholesterol in differentiating the type of effusion.

Materials and methods

This cross-sectional study involving 72 patients was undertaken in a tertiary center in Nepal for a duration of 2 years. On the basis of Light's, Heffner's, etiological, and pleural fluid cholesterol criteria, pleural effusion was classified as exudative or transudative. The findings were then evaluated to determine the diagnostic value of each approach in identifying the effusion type and comparing them on the basis of sensitivity, specificity, positive predictive value and negative predictive value.

Result

Pleural fluid cholesterol detected effusion as exudative with sensitivity of 91.94% and specificity of 80.00% against Light's criteria; with a sensitivity of 98.28% and specificity of 85.71% against the etiological diagnosis. Additionally, against the etiological diagnosis, sensitivity of both Light's and Heffner's criteria was 100%; however, specificity was 71.43% and 64.29% respectively, which is far less than that of pleural fluid cholesterol (85.71%). Furthermore, pleural fluid cholesterol was also found to have better results than protein ratio, LDH ratio and pleural fluid protein ratio in determining the type of effusion.

Conclusion

When considering the avoidance of confusing outcomes in equivocal instances and cost effectiveness in developing nations, pleural fluid cholesterol can be one of the most useful alternative diagnostic methods for differentiating between exudative or transudative effusions.

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Tuberculosis is one of the most common observed causes of exudative pleural effusions.

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A patient with an effusion when classified according to different criteria can yield different results.

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The number of patients classified as exudative or transudative effusion varies according to different parameters used.

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Pleural cholesterol has better sensitivity, specificity, PPV and NPV in differentiating pleural effusion.

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Analysis of the pleural cholesterol can become one of the best diagnostic tools to differentiate the type of effusion.

Evaluation of a new multiple regression model based on biochemical parameters for the distinction of canine exudates and transudates

BACKGROUND

The classification of effusions in human medicine currently uses biochemical parameters of verified analytical accuracy, while veterinary medicine is traditionally guided by protein content (TP) and total nucleated cell count (TNCC) in the effusion, without solid scientific support.

OBJECTIVE

We aimed to assess the accuracy of the current veterinary classification system to distinguish transudates from exudates and create new tools involving biochemical parameters that better classify canine cavitary effusions.

METHODS

Clinical, laboratory, and imaging data from 250 canine pleural and peritoneal effusions were retrospectively and prospectively collected, organized, and statistically evaluated. Multiple logistic regression analysis was performed using biochemical and cellular parameters.

RESULTS

For identifying exudates, the accuracy (87.7%, n = 204) of the best traditional classification system (TNCC > 3000 cells/μL) was similar to that of the individual biochemical cutoff values with the greatest accuracy in the abdominal cavity (eg, cholesterol, CHO-E > 40.1 mg/dL, 87.3%, n = 55). The accuracy of albumin (ALB-E > 0.8 g/dL) in the pleural cavity was nonetheless higher (100%, n = 23). The best multiple predictive models for any cavity used the percentage of neutrophils and CHO-E (n = 72), presenting an accuracy, sensitivity, and specificity for the diagnosis of exudate of 88%, 96%, and 67%, respectively.

CONCLUSIONS

Biochemical classification of pleural effusions has a higher accuracy than the traditional system (based on TP and TNCC). Utility and cutoff of analytes are different for each cavity. Implementing a multiple regression model or establishing ratios or gradients with concurrent serum values adds no significant improvement in the diagnostic potential of distinguishing transudate and exudates in dogs.

Use of cholesterol and soluble tumour markers CEA and syndecan-2 in pleural effusions in cases of inconclusive cytology

Aims

In order to improve diagnostics in pleural effusions, additional value of effusion cholesterol, carcinoembryonic antigen (CEA) and syndecan-2 assays to cytology was studied.

Methods

Biomarkers were measured in effusion supernatants from 247 patients, of whom 126 had malignant pleural involvement, and their additional diagnostic efficacy to cytology was assessed.

Results

Syndecan-2 measurement, although gave detectable concentrations in all effusions with highest median value in mesotheliomas, was non-discriminative between different pathological conditions. CEA concentrations exceeding 5 ng/mL cut-off point indicated carcinomas, regardless of pleural involvement, which gave a sensitivity of 62% and specificity of 100% for carcinoma. Cholesterol concentration over 1.21 mmol/L cut-off value indicated neoplastic pleural involvement with 99% sensitivity and ‘merely’ 69% specificity, the latter mainly due to raised levels being associated also with benign inflammatory effusions. Combined CEA and cholesterol determinations increased the sensitivity for diagnosing carcinomatosis from 70% with cytology alone to 84% and established the correct diagnosis in 16 of 31 carcinomatosis cases with inconclusive cytology. Cholesterol measurement alone, with elevated level, in combination with absence of substantial number of inflammatory cells in effusion sediment proved to be a magnificent marker for neoplastic pleural involvement with 99% efficacy, and recognised all 36 such cases with inconclusive cytology.

Conclusions

Simultaneous measurement of CEA and cholesterol concentrations in effusion, or at least cholesterol alone, in combination with non-inflammatory fluid cytology, provides additional specific information about neoplastic pleural involvement, and can therefore be used as an adjunct to cytology, above all, in inconclusive cases.

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.

Can cholesterol be used to distinguish pleural exudates from transudates? evidence from a bivariate meta-analysis

Background

Many studies have investigated whether pleural cholesterol levels can aid in diagnosis of pleural exudates, and the results have varied considerably. To gain a more reliable answer to this question, we meta-analyzed the literature on using pleural cholesterol or the ratio of cholesterol in pleural fluid to cholesterol in serum (P/S cholesterol ratio) as diagnostic tests to help identify pleural exudates.

Methods

Literature databases were systematically searched for studies examining accuracy of pleural cholesterol or P/S cholesterol ratios for diagnosing pleural exudates. Data on sensitivity, specificity, positive/negative likelihood ratio (PLR/NLR), and diagnostic odds ratio (DOR) were pooled using bivariate-effects models. Summary receiver operating characteristic (SROC) curves and area under the curve (AUC) were used to summarize overall test performance.

Results

Our meta-analysis included up to 20 studies involving 3,496 subjects. Summary estimates for pleural cholesterol in the diagnosis of pleural exudates were as follows: sensitivity, 0.88 (95%CI 0.84 to 0.92); specificity, 0.96 (95% CI 0.92 to 0.98); PLR, 20.31 (95% CI 11.21 to 36.78); NLR, 0.12 (95% CI 0.09 to 0.17); DOR, 167.06 (95% CI 76.79 to 363.95); and AUC 0.97 (95% CI 0.95 to 0.98). The corresponding summary performance estimates for using the P/S cholesterol ratio were as follows: sensitivity, 0.94 (95% CI 0.92 to 0.96); specificity, 0.87 (95% CI 0.83 to 0.91); PLR 7.46 (95% CI, 5.47 to 10.19); NLR, 0.07 (95% CI 0.05 to 0.10); DOR, 107.74 (95% CI 60.91 to 190.60); and AUC 0.97 (95% CI 0.95 to 0.98).

Conclusions

Both pleural cholesterol level and the P/S cholesterol ratio are helpful for the diagnosis of pleural exudates. Nevertheless, the results of pleural cholesterol assays should be interpreted in parallel with the results of traditional tests and clinical information.

Diagnostic value of mesothelin in pleural fluids: comparison with CYFRA 21-1 and CEA

CYFRA 21-1 and CEA have been applied for the differential diagnosis of malignant pleural mesothelioma (MPM). The soluble mesothelin-related peptide (SMRP) has been proposed as a specific marker for distinguishing MPM from benign diseases and other malignancies in pleural effusions (PEs). In this study, we evaluated the usefulness of SMRP in PEs in the detection of mesotheliomas by comparing it with that of CYFRA 21-1, CEA, and with cytological examination. One hundred and seventy-seven consecutive patients (57 MPM, 64 metastatic tumors, and 56 benign diseases) were evaluated using commercial tests. The performance of the markers was analyzed by standard ROC analysis methods, using the area under a ROC curve (AUC) as a measure of accuracy. CYFRA 21-1 better differentiated malignant from benign effusions. The corresponding area under the receiver operating characteristic curve was 0.87, while it was 0.74 for SMRP and 0.64 for CEA (p < 0.001). Conversely, SMRP differentiated MPM from all other PEs better than both CYFRA 21-1 and CEA (AUC = 0.84, 0.76, and 0.32, respectively, p = 0.003). Low levels of CEA were associated with a MPM diagnosis. The AUC for differentiating MPM from metastases was 0.81 for SMRP, 0.61 for CYFRA 21-1, and 0.20 for CEA (p < 0.001). In cases with negative or suspicious cytology, SMRP and CYFRA 21-1 identified 36/71 and 46/66 malignant PEs (29 and 31 MPM, respectively). Only 1 MPM showed a high CEA concentration. No single marker showed the best performance in any comparison. Results suggest that SMRP could improve CYFRA 21-1 and CEA accuracy in the differential diagnosis of MPM.

Pleural fluid cholesterol in differentiating exudative and transudative pleural effusion

Objectives. To study the diagnostic value of pleural fluid cholesterol in differentiating transudative and exudative pleural effusion. To compare pleural fluid cholesterol level for exudates with Light's criteria. Design. Cross sectional descriptive study. Settings. Medical wards of Tribhuvan University Teaching Hospital. Methods. Sixty two cases of pleural effusion with definite clinical diagnosis admitted in TUTH were taken and classified as transudates (19) and exudates (43). The parameters pleural fluid protein/serum protein ratio (pfP/sP), pleural fluid LDH/ serum LDH ratio, pleural fluid LDH (pfLDH) and pleural fluid cholesterol (pCHOL) were compared with clinical diagnosis with regard to their usefulness for distinguishing between pleural exudates and transudates. Results. The pCHOL values determined were 1.92 ± 0.75 for exudates, 0.53 ± 0.28 for transudates, the differences between the transudates and others are statistically significant (P < 0.0001). It is seen that pfP/sP ratio has a sensitivity of 81.4% and specificity of 82.6%; pfLDH/sLDH ratio has a sensitivity of 86% and specificity of 94.7% and pCHOL with sensitivity of 97.7% and specificity of 100% for differentiating exudative and transudative PE. Conclusion. The determination of pCHOL is of great value for distinguishing between pleural exudates and transudates and should be included in routine laboratory analysis of pleural effusion.

Cholesterol in pleural exudates depends mainly on increased capillary permeability

Pleural fluid (PF) cholesterol is a useful parameter to differentiate between pleural transudates and exudates, although the pathophysiologic mechanisms for its increase in exudates are not fully understood. We aim to elucidate the cause of this increase by analyzing the levels of cholesterol-high-density lipoproteins (HDLs), low-density lipoproteins (LDLs), apolipoprotein A (ApoA), and apolipoprotein B (ApoB)-in PF and blood as well as the number of leucocytes and red cells in the PF. We studied 259 patients with pleural effusion (57 transudates and 202 exudates). The correlations of the pleural and serum (S) levels of these parameters were analyzed, with the pleural cholesterol fractions as the dependent variables and their levels in blood and the pleural/serum protein ratio (P/S prot ratio) as the independent variables. The pleural fluid cholesterol levels (PFCHOL) correlated with their blood levels and the capillary permeability (r=0.885). No significant differences were found between the percentage of LDL, with regard to total cholesterol in the serum [SCHOL], and the same percentage in the exudates, between the PF/S LDL ratio (0.46) and the PF/S CHOL ratio (0.48), or between the PF/S ApoB ratio and the PF/S LDL ratio. The percentage of PF cholesterol bound to HDL and LDL was significantly higher (91.9%) than in the blood (90%). No significant correlations were found between any of the lipids studied and the number of erythrocytes and leucocytes. In conclusion, the PFCHOL may be predicted from the SCHOL, and the capillary permeability may be reflected by the PF/S prot ratio.