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Published on: November 10, 2023
Useful clinical biological markers in diagnosis of pleural effusions in children
1Hospital Universitari Vall d'Hebron, Barcelona, Spain. rsegura@hg.vhebron.es
Insights
Biochemical markers help diagnose pleural effusions, distinguishing exudates from transudates. Specific markers aid in diagnosing tuberculosis, malignancy, and managing complicated effusions, with a call for pediatric population studies.
Area of Science:
- Pulmonology
- Clinical Chemistry
- Diagnostic Medicine
Background:
- Pleural effusion diagnosis hinges on differentiating exudates and transudates.
- Light's criteria, using protein and LDH, are standard but can be confounded by diuretics.
- Alternative markers and specific tests are needed for accurate etiological diagnosis.
Purpose of the Study:
- To review the clinical utility of biochemical markers in diagnosing and managing pleural effusions.
- To highlight limitations of current diagnostic criteria and explore alternative markers.
- To emphasize the need for pediatric-specific validation of diagnostic markers.
Main Methods:
- Literature review of prospective studies on biochemical markers for pleural effusion diagnosis.
- Analysis of marker performance in differentiating effusion types and specific etiologies.
- Discussion of marker utility in managing complicated parapneumonic effusions and other conditions.
Main Results:
- Light's criteria can misclassify effusions in patients on diuretics; serum-to-pleural fluid albumin gradient is a useful alternative.
- Pleural fluid protein concentration >30 g/L is effective when only pleural fluid tests are available.
- Adenosine deaminase and interferon-g are accurate for tuberculous pleuritis; tumor markers aid malignancy detection.
- Amylase, triglycerides, pH, glucose, and LDH levels are valuable for specific effusion types and management decisions.
- Neutrophil-derived enzymes show potential for early detection of complicated effusions requiring drainage.
Conclusions:
- Biochemical markers are crucial for diagnosing and managing pleural effusions, offering alternatives to Light's criteria in specific scenarios.
- Specific markers like adenosine deaminase, interferon-g, and tumor markers improve etiological diagnosis.
- Pleural fluid pH is a key indicator for managing complicated parapneumonic effusions, and novel markers are emerging.
- Further research is needed to validate these markers in the pediatric population due to differing etiological prevalence.
Abstract:
In a patient with an undiagnosed pleural effusion, the first question to answer is whether the fluid is an exudate or a transudate. This is usually determined by means of Light's criteria, which differentiate transudative effusions from exudative effusions by measuring the levels of total protein and lactate dehydrogenase in the pleural fluid (PF) and serum. In patients under diuretic treatment, Light's criteria misclassify transudates as exudates, but the serum to pleural fluid albumin gradient usually remains above 12 g/L. When tests are done only in PF, protein concentration >30 g/L performs at least as well as the other individual markers. To diagnose tuberculous pleuritis among exudates, PF adenosine deaminase and PF interferon-g exhibit high diagnostic accuracy. When malignancy is suspected the addition of tumour markers to the results of cytologic analysis increases the rate of detection. Other biochemical markers are useful in specific circumstances involving pleural effusion, such as amylase in effusions due to pancreatitis, or oesophageal rupture, and triglycerides in chylothorax. Several PF markers are associated with complicated parapneumonic effusion - e.g. low PF pH and glucose, and high PF LDH activity -- although PF pH appears to be the best biochemical aid in decisions regarding chest tube drainage. Recent reports suggest that neutrophil-derived enzymes (polymorphonuclear elastase and myeloperoxidase) can be useful as early indicators of the need of chest tube insertion; however these findings must be confirmed in large series. This review discusses the clinical usefulness of biochemical markers in the diagnosis and management of pleural effusions. The vast majority of prospective studies in this field have been conducted in adults and, although the mechanisms of pleural effusion production do not differ in children and adults, the prevalence of each etiologic cause does. Therefore it seems advisable to confirm or recalculate the predictive values of each marker in the paediatric population.
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