Difference Between Exudate and Transudate

Our lung system consists of two lungs. Both our lungs are covered by a double membrane called the pleural membrane. The space between the lungs and a pleural membrane is called pleural space.


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A dysfunction in the human body may lead to the accumulation of two types of fluid in the pleural space. These are called Exudate and Transudate. 

Exudate vs Transudate

The difference between exudate and transudate is that if the protein level of a patient’s serum is higher than 35 grams per liter then the fluid is an exudate while on the other hand if the protein level of a patients serum is less than 25 grams per liter then the serum is a transudate. 

Exudate vs Transudate

Exudate is also referred to as pus. It is a kind of fluid that leaks out of the body’s blood vessels and accumulates in the tissues. This fluid leakage is made up or consists of proteins, plasma, cells, and other solid materials.

Exudates often ooze or leak out via cuts from wounds or swollen areas of infection or inflammation. 

Transudate is a type of fluid that is forced out of the walls of blood vessels due to a lot of pressure in the veins and capillaries. The fluid is also called the filtrate of blood.

It escapes the blood vessels and accumulates near the body’s tissues as edema. Edema refers to a kind of swelling.

Comparison Table

Parameters Of ComparisonExudateTransudate
AppearanceThe fluid in this case appears to be turbid and bloody.The fluid leakage, in this case, seems to appear clear, place, and yellow.
Protein Level The protein level in the fluid is more than 30 grams per liter.The amount of protein present in the fluid is less than 30 grams per liter.
SymptomsThe symptoms of exudate are:
•Shortness of breath 
•Chest pain 
•Fast breathing 
The symptoms of transudate are:
•Difficult breathing
•Pleurisy or painful breathing
CauseExudate can be caused due to different kinds of pulmonary infections.Transudate can be caused due to increased pulmonary capillary pressure. 
Specific Gravity The specific gravity of exudate is more than 1.015.The specific gravity of a transudate is less than 1.015.

 What is Exudate?

Exudate is a turbid and bloody fluid that leaks through the blood vessels. The fluid leakage accumulates into the tissues of the body. The fluid also forms an inflammation which is called pus. 

The characteristics of an exudate:

  • Cholesterol level – More than or equal to 1.2 Milli mole per liter.
  • Protein level – More than or equal to 30 grams per liter.
  • Glucose level – low amount of concentration.
  • LD activity – More than 0.67 in concentration.
  • Specific gravity – More than a concentration of 1.015. 

Exudate is caused due to a number of reasons. There are different causes for watery fluid (transudate) and protein-rich (exudate) fluid. Causes of protein-rich fluid are cancer, kidney failure, inflammatory disease, pneumonia, and pulmonary embolism.

Constituents of exudate are:

  • Water 
  • Electrolytes
  • Proteins 
  • Nutrients 
  • White blood cells 
  • Inflammatory mediators 
  • Proteases 
  • Microorganisms
  • Growth factors 

Symptoms of exudate are: 

  • Pain in the chest.
  • Fast breathing.
  • Painful breathing.
  • Shortness of breath.
  • Orthopnea (difficulty in breathing when lying down flat). 

Exudate leaks out of certain injured areas, infected areas, or inflated areas due to infections or wounds. It is called pus and is filled with protein fluid. A few examples of exudate are latex, resins, gums, and saps. 

What is Transudate?

Transudate is a pale, yellow, and quite clear fluid. It is often referred to as a filtrate of blood. The increased pressure in the blood vessels causes the leakage of this type of fluid which later accumulates in the tissues.

The characteristics of a transudate are:

  • Cholesterol level – Lesser than 1.2 Milli mole per liter.
  • Protein level – Lesser than 30 grams per liter.
  • Glucose level – high amount of concentration.
  • LD activity – Less than 0.67 in concentration.
  • Specific gravity – Less than a concentration of 1.015. 

Transudate effusion is caused due to a number of various factors. One of the main factors in heart failure. The other common causes of watery fluid are cirrhosis, heart failure, post-open heart surgery, and pulmonary embolism.

Here are a few other common causes of transudate effusion:

  • Nephritic syndrome.
  • Myxedema.
  • Constructive pericarditis.
  • Superior vena cava obstruction.
  • Peritoneal dialysis.

Symptoms of transudate fluid are: 

  • Rough and dry cough.
  • Trouble in breathing.
  • Pleurisy.
  • Trouble in the chest area.
  • Presence of edema (swelling).

Constituents of transudate are:

  • Macrophages
  • Mesothelial cells
  • Lymphocytes
  • Watery solution 
  • A few nucleated cells
  • Protein 
  • Cholesterol 
  • Primary cells 

Transudate effusion refers to the fluid that is leaked into the space between the two membrane coverings of the lung. It has low protein concentration and fewer cells. It could lead to liver diseases and kidney diseases.

Main Differences Between Exudate and Transudate 

  1. Exudate has a high level of protein while on the other hand, the protein level in a transudate is comparatively less. 
  2. The cholesterol level in an exudate is more than 1.2 millimoles per liter whereas the cholesterol level in a transudate is less than 1.2 millimoles per liter.
  3. Exudate has a low glucose level while on other hand, a transudate has a high glucose level.
  4. Exudate witnesses a high LD activity while on the other hand a transudate witnesses a low LD activity.
  5. Exudate appears to be bloody and turbid while on the other hand, transudate is clear and yellowy.


  1. https://www.magonlinelibrary.com/doi/abs/10.12968/bjcn.2003.8.Sup3.11577
  2. https://thorax.bmj.com/content/56/11/867.abstract
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