Pleural C-reactive Protein Research Articles

Combining high-resolution CT parameters and inflammatory markers to predict spread through air spaces in lung cancer.

To explore the predictive value of high-resolution computed tomography (CT) parameters and inflammatory markers for spread through air spaces (STAS) in lung cancer patients. A retrospective analysis was conducted on 72 lung cancer patients with STAS and 128 STAS-negative patients treated during the same period. Differences in high-resolution CT indicators and inflammatory markers between the two groups were assessed. Binary logistic regression was used to analyze the relationship between these indicators and STAS positivity. Receiver operating characteristic (ROC) curve analysis was performed to assess the predictive efficacy of these indicators for STAS positivity. Patients in the STAS-positive group exhibited a higher prevalence of leaf signs, pleural traction signs, and blurred tumor-lung boundaries than the STAS-negative group (P<0.05). Additionally, the STAS-positive group had elevated levels of the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII), interleukin-6 (IL-6), and C-reactive protein (CRP), alongside a lower lymphocyte-to-monocyte ratio (LMR) (P<0.05). The combined predictive model incorporating pleural traction sign, LMR, NLR, PLR, SII, IL-6, and CRP yielded an area under the curve (AUC) of 0.977, with a sensitivity of 94.4% and a specificity of 90.8%. The integration of high-resolution CT parameters with inflammatory markers demonstrates significant value in predicting STAS positivity in lung cancer patients, with the combined predictive model showing superior performance.

Role of CRP as a marker for discrimination of exudative and transudative pleural effusion.

Differentiation between exudative and transudative pleural effusion is sometime problematic. This study aimed to evaluate the diagnostic value of C-reactive protein (CRP) in differentiation of exudative and transudative pleural effusion. This is an analytical epidemiologic cross-sectional study that evaluates the role of CRP in differentiating transudative and exudative pleural effusion. Patients were divided into two groups of exudates and transudates, based on Light's criteria. The pleural effusion CRP levels were compared between the two groups. SPSS software version 16 was used for statistical analysis. The significance level was considered p<0.05. A total of 169 patients with pleural effusion enrolled in the study. Based on Light's criteria, 108 patients (63.9%) had exudative pleural effusion and 61 (36.1%) had transudative pleural effusion. The level of CRP in the pleural fluid of patients in the exudative and transudative groups was 13.3±37.1 and 3.5±4.3mg/dl, respectively (p=0.008). The 3.31 mg/dl cut-off point of CRP level of pleural effusion had the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 96.3%, 72.1%, 86% and 91.7% respectively. The results obtained in our study shows that the level of CRP in the effusion fluid can be helpful in differentiating exudative from transudative pleural effusions.

Diagnostic value of pleural C-reactive protein levels in assessing severity of pediatric parapneumonic effusions

The immediate determination of complicated parapneumonic effusion is featured by instant remedial advantages. Consequently, we attempted to evaluate whether C-reactive protein (CRP) in pleural fluid can ameliorate the identification of cases with parapneumonic effusions that eventually require intervention. Patients and methods. A case-control study enrolled 43 patients with parapneumonic effusions from the inpatient ward and emergency room of Ain Shams Pediatric University Hospital, Egypt. Twenty of those patients had complicated effusions (complicated parapneumonic pleural effusion, CPPE), and 23 had uncomplicated parapneumonic pleural effusions (UCPPE). The differentiation characteristics of pleural fluid biochemical parameters as well as pleural CRP were estimated. Pleural fluid parameters were applied to classify cases of CPPE or UCPPE. ROC analysis established CRP setting to distinguish between both groups. Results. Pleural CRP was significantly higher in CPPE and empyema (48.97 mg/L) than in UCPPE (7.75 mg/L). The optimal cut-off point between CPPE and UCPPE in relation to pleural CRP was found to be 12.26 mg/L with a sensitivity of 95.00%, specificity of 95.65%, and AUC of 94.8%. Conclusion. Pleural fluid CRP can indeed be a beneficial spare test in pleural effusions and contribute to the differential diagnosis of CPPE and UCPPE. Key words: parapneumonic effusion, empyema, pleural CRP, pediatrics

Diagnostic Accuracy of Pleural Fluid Cytology, Carcinoembryonic Antigen and C-Reactive Protein Together in Patients With Pulmonary Metastases and Malignant Pleural Effusion.

Pleural effusion (PE) has a heterogeneous aetiology, and differential diagnosis between benign and malignant disease may require invasive procedures in up to 60% of cases. The sensitivity of pleural cytology is limited, and several strategies have been tested to reduce the need of invasive diagnostic approaches. The aim of this study was to evaluate the usefulness of pleural fluid cytology, compared to, and combined with, carcinoembryonic antigen (CEA), C reactive protein (CRP), and lactate dehydrogenase (LDH) assay of pleural fluid (PF) in patients with a history of cancer, exudative non-purulent PE, and suspicion of malignant PE on imaging studies. The medical records of 40 patients with pulmonary metastases and malignant PE, and 57 controls with benign exudative PE were reviewed. All the patients underwent pleural cytology and CEA, CRP, and LDH assay before VATS-guided biopsy. The sensitivity and specificity were 55.0% and 98.2% (cytology), 35.0% and 98.2% (CEA), 92.5% and 71.9% (CRP), 70.0% and 54.4% (LDH). The multivariate analysis excluded LDH, and the final AUC (cytology+CEA+CRP) was 0.894. In all patients with a history of cancer and PE of uncertain origin, the combination of PF cytology plus pleural CEA and CRP assay together should be suggested to recognize malignant plural effusion (MPE), minimising the use of unnecessary invasive investigations.

Diagnostic performance of C-reactive protein for parapneumonic pleural effusion: a meta-analysis.

Parapneumonic pleural effusion (PPE) refers to effusion secondary to lung infection, the accurate diagnosis of which remains a clinical challenge. Many studies have suggested that the C-reactive protein (CRP) may be useful for diagnosing PPE, but the results have varied. This study aimed to summarize the overall diagnostic ability of serum/pleural CRP for PPE through a meta-analysis. Eligible studies were searched for within PubMed, EMBASE, and other databases up to March 1, 2018. The main diagnostic indexes, sensitivity, specificity, positive likelihood ratio/negative likelihood ratio (PLR/NLR), and diagnostic odds ratio (DOR), were then pooled from the individual studies. The summary receiver operating characteristic curves and area under the curve (AUC) were used to summarize the overall test performance. Eighteen publications were included in this meta-analysis. Summary estimates of the diagnostic performance of pleural CRP for PPE were as follows: sensitivity, 0.80; specificity, 0.82; PLR, 4.51; NLR, 0.25; DOR, 18.26; and AUC, 0.88. The AUC of serum CRP in diagnosing PPE was 0.79. The diagnostic indexes for pleural CRP in differentiating complicated PPE (CPPE) from uncomplicated PPE were as follows: sensitivity, 0.65; specificity, 0.85; PLR, 4.26; NLR, 0.41; DOR, 10.38; and AUC, 0.83. There was no evidence of publication bias. Both serum and pleural CRP help to diagnose PPE but with moderate diagnostic ability. Pleural CRP measurements also can aid in differentiating CPPE from uncomplicated PPE. However, the results of the CRP assay should be interpreted with additional biomarker tests.

Prognostic Index for Survival in Patients with Advanced Non-Small-Cell Lung Cancer Treated with Third-Generation Agents

We retrospectively evaluated clinical data from patients with advanced non-small-cell lung cancer (NSCLC) treated with third-generation chemotherapy agents prior to treatment, to determine a reliable method for predicting prognosis in such patients. We analyzed 100 patients who received third-generation agents (paclitaxel, docetaxel, gemcitabine, irinotecan, and vinorelbine) for the treatment of advanced NSCLC. Factors significantly related to prognosis were evaluated using the Cox regression model, and the prognostic index (PI) was determined by combining these factors. The mean follow-up duration was 12.6 months (0.2-67.0 months). Multivariate analysis identified pleural effusion, absolute neutrophil count (ANC), and C-reactive protein (CRP) level as significant factors that independently contribute to prognosis in patients with advanced NSCLC treated with third-generation agents (p < 0.05). The PI was calculated using these 3 factors, according to the following formula: PI = 0.581 × pleural effusion + 0.125 × ANC + 0.105 × CRP. The death rate in the group with the highest PI scores was significantly higher than in the group with the lowest scores (p < 0.001). Pleural effusion, ANC, and CRP level were the most important factors that contributed to prognosis following chemotherapy with third-generation agents in patients with advanced NSCLC. The PI is suggested to be an appropriate index to predict the prognosis of patients with NSCLC.

P2.04-054 Pleural CEA and C-Reactive Protein in Patients with Lung Metastases and Malignant Pleural Effusion. A Prospective Case-Control Study: Topic: Esophageal Cancer and Other Malignancies

Malignant pleural effusion (PE) is common cancer patients, and may require invasive investigations. The aim of this study was to evaluate the diagnostic utility of pleural carcinoembryonic antigen (pCEA) and pleural C-reactive protein (pCRP) assay in cancer patients with PE. We prospectively measured both pCEA and pPCR in 41 consecutive patients with a history of cancer and PE (cases). Controls were 41 age- and sex-matched patients with confirmed benign PE. There were 52 (63.4%) men and 39 (47.6%) women, with an overall median age of 71 years (range 40-88 years). The age (p=0.943) and male-to-female ratio (p=0.254) did not differ significantly between groups. pCEA (34.9±104.8 vs. 1.5±1.3 ng/mL; p<0.0001) was higher in patients with malignant PE, while pCRP was higher (11.7±7.2 vs. 5.5±3.4 mg/L; p=0.0001) in controls. The results are reported in the Table (95% CI). A weak inverse correlation was found between pCRP and pCEA (R= ‒0.107, p=0.505). The relative linear regression equation (Figure) was pCPR=11.725‒0.573 pCEA, suggesting that the two markers were independent parameters.View Large Image Figure ViewerDownload Hi-res image Download (PPT) The measurement of pCRP+pCEA together represents an accurate and easy to perform tool useful in differentiating between benign and malignant PE, and should be suggested in all cancer patients requiring PE analysis.

Diagnostic value of procalcitonin and C-reactive protein in differentiation between some benign and malignant pleural effusions

Pleural effusion is relatively common clinical condition that requires differential diagnosis. It is defined as collection of fluid in pleural space. Pleural effusion is often diagnostic dilemma for the physician.The aim of the study was to assess the procalcitonin (PCT) and C-reactive protein (CRP) levels in serum and pleural fluid to evaluate their usefulness in the differentiation among benign and malignant pleural effusions.This study was conducted in Chest Department, Tanta University Hospital, it included 54 adult patients with pleural effusions of different etiologies, 8 transudative effusion, 14 para-pneumonic effusion, 14 tuberculous effusion and 18 malignant effusion. We measured serum and pleural procalcitonin and C-reactive protein by ELISA.The mean serum and pleural fluid procalcitonin (PCT) levels in parapneumonic effusions were significantly higher compared with transudative, tuberculous and malignant pleural effusions p<0.05. A significant positive correlation between serum and pleural fluid PCT levels was observed in the studied groups. The mean serum and pleural fluid CRP concentration were significantly lower in malignant and transudative pleural effusion than tuberculous and para-pneumonic effusion p<0.05.Significant positive correlation between serum and pleural fluid CRP levels was observed in the studied groups. Procalcitonin levels in serum and pleural effusion were significantly lower in malignant effusion compared to para-pneumonic pleural effusion and CRP levels were significantly lower compared to other types of exudative pleural effusion.

Diagnostic Value and Prognostic Significance of Pleural C-Reactive Protein in Lung Cancer Patients with Malignant Pleural Effusions

PurposeC-reactive protein (CRP) has been implicated in various inflammatory and advanced malignant states. Increased serum CRP (s-CRP) levels have been shown to be associated with independent prognostic factors for survival in patients with advanced lung cancer. However, only few studies have focused on the role of CRP in pleural effusions. This study aimed to evaluate the diagnostic and prognostic value of pleural CRP (p-CRP) in lung cancer patients with malignant pleural effusion (MPE).Materials and MethodsPleural effusion (PE) samples were collected from patients with MPE (68 lung cancers; 12 extrathoracic tumors), and from 68 patients with various benign conditions (31 with pneumonia; 37 with tuberculosis). Concentrations of p- and s-CRP were measured by enzyme-linked immunosorbent assay. CRP level in pleural fluid and its association with survival were examined.Resultsp-CRP levels correlated with s-CRP levels (r=0.82, p<0.0001). For the differential diagnosis of MPE and benign PE, the area under the receiver operating characteristic curve was greater for p-CRP (0.86) than for s-CRP (0.77). High p-CRP expression significantly correlated with shorter overall survival (p=0.006). P-CRP was independent prognostic factor significantly associated with overall survival on multivariated analysis (p=0.0001). The relative risk of death for lung cancer patients with high p-CRP levels was 3.909 (95% confidence interval, 2.000-7.639).ConclusionP-CRP is superior to s-CRP in determining pleural fluid etiology. Quantitative measurement of p-CRP might be a useful complementary diagnostic and prognostic test for lung cancer patients with MPE.

C-Reactive Protein and Reendothelialization

See related article, pages 1452–1459 Disruption of the endothelium and its subsequent dysfunction appears to set the stage for atherogenesis.1 The maintenance of vascular homeostasis depends in part on a balance between endothelium-derived relaxing and contracting factors. Alterations in this balance lead to inflammation and the formation of fatty streaks and fibrous plaques. The diminished production or availability of nitric oxide (NO) appears paramount to setting the stage for inflammation and vascular injury. In addition to its vasodilatory effect on the vasculature, endothelium-derived NO promotes endothelial cell growth, survival and migration,2 stimulates angiogenesis and neovascularization in part by endothelial progenitor cell (EPC) recruitment,3 inhibits leukocyte adhesion to the endothelium,4 maintains vascular smooth muscle in a nonproliferative state,5 and limits platelet aggregation and thrombosis.6 Maintenance of an intact and functional endothelium protects against vascular disease while its disruption is detrimental. The study by Schwartz et al,7 in this issue of Circulation Research , adds to our understanding of how C-reactive protein (CRP) works to promote vascular pathology by inhibiting NO synthesis. CRP, long regarded as an acute phase protein and an active participant in the innate immune system, has more recently been linked to the development of cardiovascular disease.8 On the basis of several prospective epidemiologic studies, circulating high sensitivity CRP has emerged as an independent predictor of cardiovascular disease risk in various subgroups of patients, including those without overt cardiovascular disease, patients with stable angina or acute coronary syndromes, and in those with the metabolic syndrome.9–12 In primary prevention, CRP confers additional prognostic value at all levels of Framingham risk score and blood pressure.13,14 However, whether or not CRP plays a direct biological role in the initiation and progression of atherosclerosis is controversial.15,16 …

The biological effects of CRP are not attributable to endotoxin contamination: evidence from TLR4 knockdown human aortic endothelial cells

C-reactive protein (CRP) is the prototypic marker of inflammation and a strong predictor of cardiovascular events in humans. There are questions regarding the validity of the biological effects reported for CRP, in spite of adherence to rigorous control measures minimizing endotoxin [lipopolysaccharide (LPS)] contamination in these in vitro studies. In this study, we addressed the key question of endotoxin contamination in CRP preparations using Toll-like receptor 4 (TLR4) knockdown endothelial cells. Human aortic endothelial cells (HAECs) transfected with prevalidated TLR4 small interfering RNA (siRNA) and scrambled siRNA controls were challenged with pleural fluid-derived CRP or LPS for 12-16 h. Secreted interleukin-6 (IL-6), IL-1beta, IL-8, and plasminogen activator inhibitor-1 (PAI-1) levels and endothelial Nitric oxide synthase (eNOS) activity were determined. TLR4 knockdown in HAECs significantly decreased LPS-induced IL-1beta, IL-6, and IL-8, whereas the stimulatory effects of CRP were similar in both scrambled control and TLR4 knockdown cells. Furthermore, CRP significantly stimulated PAI-1 levels in both control and TLR4-transfected cells and inhibited eNOS activity, whereas LPS effects were negated in TLR4-transfected cells. The data presented cogently demonstrate and further confirm that the biological effects of CRP on HAECs are independent of LPS and thus are attributable to native protein per se. This is the first study to positively authenticate the significance of earlier in vitro reports on CRP biological effects.

Diagnostic Value of Procalcitonin and C-Reactive Protein in Differentiation of Pleural Effusions

Background: Malignancies are a common and important causes of exudative pleural effusions. Several tumor markers have been studied because the pleural fluid cytology and pleural biopsy specimens do not provide a diagnosis in a high percentage of malignant effusions. In an attempt to overcome this limitation, procalcitonin and C-reactive protein (CRP) in pleural effusions and serum, which are known to be inflammation markers, were measured to determine if they can differentiate an exudate from trasndate as well as the diverse causes of exudative pleural effusion. Methods: 178 consecutive patients with pleural effusion (malignant 57, tuberculous 51, parapneumonic 31, empyema 5, miscellaneous benign 7, transudative 27)were studied prospectively. The standard parameters of pleural effusion and measured serum and pleural procalcitonin were examined using in immunoluminometric assay. The level of CRP in serum and pleural fluid was determined by turbidimetric immunoassay. Results: The pleural procalcitonin levels in the exudate were significantly higher than those in the transudate, and , respectively (p=0.007). The pleural CRP levels were significantly higher in the exudate than the transudate, and , respectively (p and , respectively (p=0.032). The pleural CRP levels were significantly higher in the benign effusion than in the malignant effusion, and , respectively (p and , respectively (p=0.008). Conclusion: Measuring the level of procalcitonin and CRP in the pleural fluid is helpful for differentiating between transudates and exudates. In addition, it is useful for differentiating between benign and malignant pleural effusions.

Can Intrapleural C-Reactive Protein Predict VATS Pleurodesis Failure?

Intrapleural inflammatory reaction after surgery for spontaneous pneumothorax is a key indicator whether an effective pleurodesis has been achieved. In this study, we tested the hypothesis that intrapleural C-reactive protein (CRP) might precisely quantify the postoperative pleural inflammation, offering potentially useful information for patient management. The study population consisted of 75 consecutive patients who underwent video-assisted thoracoscopic pleurectomy or pleural abrasion for spontaneous pneumothorax between April 2003 and August 2004. We assessed CRP levels in pleural and blood samples taken daily in the first 4 postoperative days. Intrapleural CRP profile was significantly lower in patients who underwent pleural abrasion, in younger patients (< 25 years) and in patients who were not drained before surgery. Patients with pleurodesis failure had a lower CRP peak with a delayed peak. Receiving operating characteristics (ROC) analysis showed that the cutoff value of intrapleural CRP for pleurodesis failure was 25 mg/l on the second postoperative day (sensitivity 87.5 %, specificity 66.6 %, positive predictive value 24.1, negative predictive value 97.7 %). Pleural CRP levels of less than 25 mg/l on the second postoperative day indicate only a moderate pleural inflammation.

Role of Pleural Fluid C-Reactive Protein Concentration in Discriminating Uncomplicated Parapneumonic Pleural Effusions from Complicated Parapneumonic Effusion and Empyema

The aim of this study was to determine whether pleural fluid C-reactive protein (CRP) is useful in distinguishing complicated parapneumonic pleural effusion (CPPE) and empyema from uncomplicated parapneumonic pleural effusions (UPPE). A total of 69 consecutive patients with parapneumonic effusions were enrolled in the study: 29 with UPPE, 29 with CPPE, and 11 with empyema. Concentrations of standard biochemical parameters together with CRP in the pleural fluid were measured using an immunoturbidimetric assay. Pleural CRP was significantly higher in CPPE (11.6 mg/dl) and in empyema (12.2 mg/dl) than in UPPE (3.9 mg/dl). A cutoff value of 8.7 mg/dl for pleural CRP in the diagnosis of CPPE and empyema resulted in a sensitivity, specificity, and area under the receiver-operating characteristic curve (AUC) of 0.80, 0.97 and 0.94, respectively. Traditional lactic dehydrogenase (LDH) > or = 1000 U/L and glucose < or = 60 mg/dl can differentiate CPPE and empyema from UPPE, with the sensitivity, specificity, and AUC achieving 0.75/0.60.1.00/1.00,0.95/0.22, respectively. However, for the detection of CPPE and empyema, the combination of pleural fluid CRP > or = 8.7 mg/dl and LDH > or = 1000 U/L was valuable in achieving a sensitivity, specificity, and AUC of 0.97/1,00/0.95. This study suggests that measurement of pleural CRP can be useful in the workup of patients with a parapneumonic effusion in order to differentiate CPPE from UPPE.

Diagnostic value of C-reactive protein in exudative pleural effusions

Background: Tests able to help in the diagnostic work-up of pleural exudates are needed. C-reactive protein (CRP) may be useful for distinguishing between benign and malignant exudates. Methods: A total of 123 consecutive patients diagnosed as having exudative pleural effusion (60 associated with malignancy and 63 benign effusions) were included in the study. Sensitivity, specificity, positive and negative predictive values (PV+, PV−), and positive and negative likelihood ratios (LR+, LR−) were established at different cut-off points. Results: Pleural fluid CRP level was 23±12 mg/l (mean±S.D.) in pleural exudates associated with malignancy and 50±33 mg/l in benign effusions ( P<0.001). With a cut-off point below 20 mg/l for malignancy, sensitivity of CRP was 0.50, specificity 0.89, PV+ 0.81, PV− 0.65, LR+ 4.50, and LR− 0.65. With a cut-off point above 45 mg/l for benign diseases, sensitivity was 0.44, specificity 0.95, PV+ 0.90, PV− 0.62, LR+ 8.89, and LR− 0.58. Conclusions: The pleural CRP level provides useful information for the study of pleural exudates. A level below 20 mg/l suggests a malignant origin and a level above 45 mg/l virtually rules out this possibility. Additional advantages of measuring CRP level are that it is an inexpensive test and is easy to perform.

Use of pleural fluid C-reactive protein in diagnosis of pleural effusions

The aims of the study were to assess whether C-reactive protein (CRP) is a sensitive marker for discriminating between transudative and exudative and pleural effusions to evaluate whether it can be used to distinguish inflammatory pleural effusions from other types of effusion.Pleural fluid and serum CRP levels were obtained in 97 patients with pleural effusion, using an immunoturbidimetric method (Olympus AU-600 autoanalyser). We compared CRP levels between transudates and exudates, inflammatory effusions and other types of effusion.According to the criteria used, 16 patients were included in the transudate group and 81 patients in the exudate group. Pleural fluid CRP levels were significantly lower in the transudate group (P<0·04; 14·9±4·9 mg l−1and 35·5±4·9 mg l−1respectively). Also, the ratio of pleural fluid to serum was significantly lower in the transudate group (P<0·009; 0·8±0·5 mg l−1and 2·8±0·7 mg l−1, respectively). In the exudate group, 35 patients had neoplastic effusions, 10 chronic non-specific pleurisy, 19 tuberculous pleurisy, 16 parapneumonic effusion and one Dressler Syndrome. When these sub-groups were compared, the parapneumonic effusion subgroup CRP levels (mean 89±16·3 mg l−1) were significantly higher than those in the other subgroups, other exudate of neoplastic effusion, tuberculous pleurisy and chronic non-specific effusion and the transudate group (P<0·0001;P<0·0001;P<0·0004 and P<0·0001, respectively). The ratio between pleural fluid and serum CRP was significantly higher in the parapneumonic effusion subgroup than in the neoplastic subgroup (P<0·0002; 6·6±2·7 mg l−1and 1±0·2 mg l−1, respectively). Pleural fluid CRP levels >30 mg l−1had a high sensitivity (93·7%) and specificity (76·5 %) and a positive predictive value of 98·4%. In the differential diagnosis of pleural effusions, higher CRP levels may prove to be a rapid, practical and accurate method of differentiating parapneumonic effusions from other exudate types. Although the high level of CRP obtained in the exudate group may be due to the number of patients with parapneumonic effusion who were included, the pleural CRP level may also be helpful in discriminating between exudative and transudative pleural effusions.

Significance of Alpha-2-Macroglobulin, Alpha-1-Acid Glycoprotein, and C-Reactive Protein in Pleural Effusion Differentiation

Background: The differentiation between exudates and transudates is fundamental when investigating the cause of pleural effusions. Acute-phase proteins could be potentially useful markers in this discrimination. Objective: The present study was designed to evaluate whether the acute-phase proteins: α₂-macroglobulin (AMG), α₁-acid glycoprotein (AAG) and C-reactive protein (CRP) are useful in investigating the pleural effusions. Methods: We prospectively measured the concentrations of the above proteins in the serum and pleural fluid of 84 consecutive patients with various diseases using a nephelometric assay. Results: Pleural effusion AMG, AAG and CRP were all significantly elevated in the group of patients with exudates compared to patients with transudates (p < 0.001, p < 0.001 and p < 0.01, respectively). An AAG value >63 mg/dl in a pleural effusion is predictive of an exudate with a sensitivity of 90% and a specificity 85%. Similarly, an AMG value >44 mg/dl in a pleural effusion is predictive of an exudate with a sensitivity and a specificity of 90% and 60%, respectively. Moreover, pleural AAG was significantly higher in cancerous exudates than in exudates and transudates of all other cause taken together (p < 0.001). Finally, to differentiate the same pleural effusion, the cut-off value of 1.0 mg/dl of pleural CRP has a sensitivity and a specificity of 74% and 74%, respectively. Conclusions: We conclude that both AAG and AMG concentrations in pleural effusions have a high sensitivity and are therefore useful parameters in distinguishing exudates from transudates, but the latter is inferior due to its unacceptably low specificity.