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What is Pleural Fluid

What is Pleural Fluid

If you are wondering what pleural fluid is, then you can find information related to this body fluid from the article given below.
Batul Nafisa Baxamusa
Last Updated: Apr 22, 2018
There are many types of serous fluids present in the body cavity that are pale yellow in color and transparent. These fluids are benign in nature and originate from the serous glands. These secretions are made up of proteins and water, sometimes they also contain mucous and serous cells.
Pleural fluid is also a type of serous fluid that is secreted by normal pleurae. The following paragraphs will cover information related to its function and the health problems related to excess production of this serous fluid.
Overview
Pleural fluid is a type of lubricant secreted by the tissues lining the lung and the chest cavity. It helps in lubricating the lungs and helps one breath normally. If there is excessive production of this fluid, it leads to inflammation of the pleura (pleuritis) or accumulation of the fluid in pleural space. This condition is usually a sign of an underlying health disorder, that causes overproduction.
Causes
It accumulates due to the above two reasons. These fluids may be produced due to the following reasons:
Transudate
When an imbalance is caused between the protein in blood that helps keep fluid in blood vessel and the pressure that helps in flow of blood out of the blood vessel, it causes fluid accumulation. This fluid is called transudate, that is mostly caused by congestive heart failure or cirrhosis. A transudate is a clear fluid that has low protein or albumin levels and there are very few cells present in this fluid.
Exudate
There are many conditions that causes inflammation of pleurae. This inflammation leads to excessive collection of fluid, known as exudate in the pleural cavity. Conditions that lead to formation of exudate include:
  • Infectious diseases caused by bacteria, viruses, fungi. For e.g. Pneumonia
  • Bleeding due to pulmonary embolism, bleeding disorders and trauma also leads to presence of blood in the fluid.
  • Inflammatory disorders like asbestosis, sarcoidosis, rheumatoid arthritis, systemic lupus erythematosus lead to pleural fluid accumulation.
  • Cancers like lymphoma, metastatic cancers
  • Miscellaneous conditions like heart transplant, lung transplant, pancreatitis, cardiac bypass surgery or idiopathic conditions.
The exudate generally appear cloudy, contain high levels of proteins or albumin as well as show increased cell count.
Symptoms of Excessive Accumulation
When one suffers from accumulation of pleural fluid, one tends to develop some signs and symptoms. However, pleural effusion generally does not cause any symptoms. Signs and symptoms of fluid accumulation may include:
  • Chest pain that worsens when one tries to take a deep breath
  • Breathing trouble
  • Shortness of breath
  • Coughing
  • Fatigue
  • Fever with chills
Tests for Diagnosis
In order to determine, whether one has developed transudate or exudate in their lungs, a battery of tests may be ordered. Transudate require no further testing as they are generally caused due to congestive heart failures, or due to liver cirrhosis. It is the exudate that require further testing. The exudate generally appears light yellow in color and has a clear appearance. When it is caused by an underlying disease or condition, it may undergo a change in appearance.
These include:
  • Involvement of the lymphatic system causes the exudate to appear milky
  • Bleeding disorders cause the exudate to turn reddish in color
  • Infections due to microorganisms and presence of white blood cells causes the exudate to appear thick and cloudy
  • The presence of high proteins and albumin levels requires further testing like blood glucose levels are checked if it is lower than normal. If yes, then it may indicate infection or presence of rheumatoid arthritis
  • High levels of lactate indicate tuberculosis or infectious pleuritis
  • Pancreatitis or malignancy is indicated by high levels of amylase
The doctor may even order total cell count, WBC differential tests, as well as cell cytology tests, to check the level of abnormal blood cells, tumor cells or immature blood cells. A gram stain or bacterial culture is ordered, in case a bacterial infection is suspected.
Pleural fluid is produced by the parietal circulation and gets absorbed by the lymphatic system. It is produced and absorbed continuously. If large quantities of this body fluid accumulate, it can lead to many health problems.