Hello and welcome to the zero to finals podcast. My name is Tom and in this episode I'm going to be

talking to you about plural effusions. And you can find written notes on this topic at zero to

finals.com slash plural effusion or in the respiratory section of the second edition of the zero to finals medicine

book. So let's get straight into it. A plural effusion is a collection of fluid in the plural

space. Plural effusions can be broadly categorized into exudative, where there's a high protein content in the fluid

of more than 30 grams per liter, and transudative where there's a lower protein content

of less than 30 grams per liter. Light's criteria are used for establishing a diagnosis of an

exudative effusion using the protein content

or the lactate dehydrogenase or LDH.

The three options for diagnosis are a plural fluid protein to serum protein ratio of greater

than 0.5, a plural fluid LDH to serum protein ratio of greater than 0.5,

a plural fluid LDH to serum LDH ratio of greater than 0.6,

or a plural fluid LDH of greater than 2 thirds of the upper limit of normal of the serum LDH.

Let's talk about the causes.

Exudative causes of plural effusions are related to inflammation.

The inflammation results in protein leaking out of the tissues into the plural space.

X meaning moving out of. The top causes are cancer,

for example lung cancer or mesothelioma, infection, for example pneumonia or tuberculosis,

and rheumatoid arthritis. Transudative causes relate to fluid moving across or shifting into the plural space,

trans meaning moving across. The top causes are congestive cardiac failure, hypoalbuminemia,

where there's a low albumin level in the blood,

hypothyroidism, and Mages syndrome.

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