In the context of pleural fluid analysis, TLC refers to the total leukocyte count. This is a measure of the total number of white blood cells present in a sample of fluid drawn from the pleural space (the area between the lungs and the chest wall). The TLC value helps differentiate between different types of pleural effusions (fluid buildup).
Understanding TLC in Pleural Effusions
The total leukocyte count is a crucial component of pleural fluid analysis. Different types of pleural effusions have characteristic TLC levels:
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Transudative effusions: These are typically caused by systemic problems like heart failure or liver disease. Most transudative effusions show a TLC of less than 1000 cells/cu.mm (as noted in one reference).
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Exudative effusions: These result from problems within the pleura itself, such as infection or cancer. A significant portion (52.44%, according to one study) of exudative effusions have a TLC greater than 1000 cells/cu.mm. However, it's important to note that a high TLC isn't solely diagnostic of an exudative effusion. Further analysis of the specific types of white blood cells (differential count) is necessary.
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Specific Effusion Types: The type of white blood cell predominantly present also provides valuable diagnostic information. For example, a high lymphocyte count (a type of white blood cell) is often associated with tuberculous pleural effusion. Lymphocyte-predominant exudative effusions are defined as those with lymphocytes making up over 50% of the total white blood cell count. Examples of TLC values with differential counts include a case where TLC was 9500 cells with neutrophils making up 76% of the count.
The procedure to obtain a sample of pleural fluid for analysis is called thoracentesis. This involves inserting a needle into the pleural space to collect the fluid.
