Introduction

All healthy humans have a small amount of pleural fluid that lubricates the space and facilitates normal lung movements during respiration. The pleural fluid normally provides lubrication between the parietal and visceral membranes and the organs contained within the space.^[1] A pleural effusion, an excessive accumulation of fluid in the pleural space, indicates an imbalance between pleural fluid formation and removal. Accumulation of pleural fluid is not a specific disease, but rather a reflection of underlying pathology. Pleural effusions accompany a wide variety of disorders of the lung, pleura, and systemic disorders. Therefore, a patient with pleural effusion may present not only to a pulmonologist but to a general internist, rheumatologist, gastroenterologist, nephrologist, or surgeon. To treat pleural effusion appropriately, it is important to determine its cause.^[2] For diagnosing and treatment plan, pleural effusions have to be classified into transudate and exudate. The routine pleural fluid evaluation usually includes determination of protein, pH, lactate dehydrogenase, glucose, and albumin levels, with adenosine deaminase levels and cell count for differential and cytological examination.^[3] If the diagnosis is not appropriate, it may result in severe complications.

The most commonly used method for differentiating exudates from transudates was established by Light et al.^[4] Fluid is considered exudative if it meets one or more of the following: (a) pleural/serum protein ratio greater than 0.5 (b) pleural/serum lactate dehydrogenase (LDH) ratio than two-thirds of the normal upper limit for serum.

Another method used for differentiating exudates from transudates was Serum - pleural effusion albumin gradient (SEAG). Albumin gradient (serum albumin concentration - pleural effusion albumin concentration).

The main purpose of this study was, to study the diagnostic role of biochemical parameters in pleural effusion. To treat pleural effusion appropriately, we have divided the pleural effusions into the transudative and exudative pleural effusions with help of various biochemical parameters.

Aim and Objectives

To analyze various biochemical parameters in pleural fluid and To correlate these Biochemical parameters with diagnosis of the patients.

Materials and Methods

The study was a hospital based descriptive study. The study was conducted over a period of one year on 100 samples. Total 100 samples were enrolled in the study. Both serum and pleural fluid samples were collected and quantitatively analyzed using semi-automated analyzer.

Results

[Figure 1] showing Comparison of clinical diagnosis of exudative pleural effusions with SEAG diagnosis and Light’s criteria diagnosis out of total 72 patients 37 were tubercular, 22 malignant and 13 patients are empty and these results was highly statistically significant with p= ˂0.0001 and these results was highly statistically significant with p= ˂0.0001. emic SEAG could only identify the 68 pleural effusion as exudative and Lights criteria identify 73 effusion as exudative. SEAG misclassify 4 tubercular effusions whereas light’s criteria misclassify only 1 CHF effusion.

[Figure 2] showing comparison of clinical diagnosis of transudative pleural effusions with SEAG diagnosis and Light’s criteria diagnosis out of 28 patients 16 were congestive heart failure cases, 09 having liver cirrhosis and 03 patients have anaemia SEAG could identify 32 effusion as transudative and Lights criteria identifies 27 effusions as transudative. SEAG misclassify 5 tuburcular effusion whereas Light’s criteria misclassify 1 tuburcular effusion.

Discussion

The present study show analysis of biochemical parameters (LDH, pH, Glucose, Triglycerides, Cholesterol, Creatinine, Amylase and ADA) in both pleural fluid and serum. Results of present study were consistent with the other study conducted by Sandeesha V et al. (2020),^[5] Das AK et al. (2009),^[6] Burgess LJ et al. (1995),^[7] Dhar MC et al (2000).^[8] According to present study Lights criteria’s specificity for exudate was 96.43% and sensitivity was 100%. SEAG criteria had specificity 96.43% and sensitivity 94.37% for exudate. However, Lights criteria had specificity of 100% and sensitivity 96.43%. SEAG criteria have specificity 94.37% and sensitivity 96.43%. Levels of glucose, ADA and LDH in pleural fluid of exudate effusions were 59.52±10.43, 54.42±16.92 and 330.3±50.06 respectively, and these results was highly statistically significant with p= ˂0.0001.

Levels of glucose, ADA and LDH in pleural fluid of transudate effusions were 78.85±11.80, 39.21.±15.12, 234.8±41.5 and these results was highly statistically significant with p= ˂0.0001.

Conclusion

It was concluded that Biochemical parameters play important role in diagnosing Pleural effusions. These markers when used collectively their diagnostic efficacy is greatly increased. The SEAG is superior to Light's criteria in identifying the transudative effusions. It is also observed that Light's criteria identified exudative effusions better than SEAG.

Source of Funding

None.

Conflict of interest

None.