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Interpretive Handbook

Test 34621 :
Bilirubin, Body Fluid


Assessing whether a body fluid specimen is exudative or transudative in nature is the initial step in determining the etiology of the fluid. Transudative fluids result from hemodynamic aberrations or oncotic changes and are associated with ultrafiltration of serum across pleural membranes. Transudates most commonly occur in association with clinically apparent conditions such as heart failure and cirrhosis. Exudative fluids tend to develop as a consequence of inflammation or malignant disorders such as tuberculosis, pneumonia, or cancer, in which capillary permeability is increased, allowing large-molecular-weight compounds to be released into the accumulating fluid. If the fluid is transudate, further diagnostic procedures are often not necessary, however the presence of an exudative fluid often triggers additional testing that may be invasive in nature.


Determination of body fluid bilirubin concentration can aid in the distinction between a transudative and an exudative fluid. Bilirubin values tend to be higher in exudates than in transudates, although there is some overlap between groups. However, a ratio of body fluids to serum bilirubin has been reported to identify exudative body fluids with sensitivity, specifically, positive predictive accuracy, and absolute accuracy equivalent to that obtained using Light's criteria for an exudative pleural fluid (pleural/serum protein ratio >0.5, pleural/serum lactate dehydrogenase ratio >0.6, and serum lactate dehydrogenase >200 U/L).


May aid in the distinction between a transudative and an exudative body fluid, when used in conjunction with other testing including serum bilirubin analysis, body fluid; serum protein ratio, body fluids; serum lactate dehydrogenase ratio, and serum lactate dehydrogenase

Interpretation Provides information to assist in interpretation of the test results

Elevated body fluid bilirubin is suggestive of an exudative fluid. This testing should be performed in conjunction with other testing including serum bilirubin analysis, body fluid:serum protein ratio, body fluids:serum lactate dehydrogenase ratio, and serum lactate dehydrogenase.


Bilirubin is photosensitive. Failure to protect from light may cause decreased results.


Contamination by blood may cause altered results in either direction.


Not applicable

The reference range has not been established for bilirubin in body fluids. The test result should be integrated into the clinical context for interpretation.


1. Elis A, Meisel S, Tishler T, et al: Ascitic fluid to serum bilirubin concentration ratio for the classification of transudates or exudates. Am J Gastroenterol 1998 Mar;93(3):401-403

2. Runyon BA: Ascitic fluid bilirubin concentration as a key to choleperitoneum. J Clin Gastroenterol 1987 Oct;9(5):543-545

3. Darwin P, Goldberg E, Uradomo L: Jackson Pratt drain fluid-to-serum bilirubin concentration ratio for the diagnosis of bile leaks. Gastrointest Endosc 2010 Jan;71(1):99-104 Epub 2009, Nov 27

4. Burgess LJ: Biochemical analysis of pleural, peritoneal and pericardial effusions. Clin Chim Acta 2004 May;343(1-2):61-84

5. Clinical and Laboratory Standards Institute: Analysis of Body Fluids in Clinical Chemistry; Approved Guideline. Clinical and Laboratory Standards Institute, Wayne, PA, 2007, CLSI document C49-A (ISBN 1-56238-638-7)