Test Catalog

Test ID: BFLA1    
Lipid Analysis, Body Fluid

Useful For Suggests clinical disorders or settings where the test may be helpful

Distinguishing between chylous and nonchylous effusions

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Measurement of cholesterol and triglycerides combined with detection of chylomicrons in body fluids is useful for diagnosing chylous effusion or differentiating from pseudochylous effusion.(1) Chylous effusions are characterized by the presence of chyle which contains chylomicrons circulating through the lymphatic system. Pseudochylous effusions do not have chylomicrons. Cholesterol concentrations in serous effusions increase over time due to chronic exudative processes that cause cell lysis or increased vascular permeability. These fluids have a milky appearance can be confused with chylous effusions. While chylous effusions often have elevated triglyceride concentrations and decreased cholesterol concentrations, identification of chylomicrons is considered the gold standard for the diagnosis.


Pleural Fluid:

Chylothorax is the name given to pleural effusions containing chylomicrons. They develop when chyle accumulates from disruption of the lymphatic system, often the thoracic duct, caused mainly by malignancy or trauma.(1) Lymph contains chylomicron rich chyle characterized by high concentrations of triglycerides. Pseudochylous effusions are the name given to milky appearing effusions that do not contain lymphatic contents but rather form gradually through the breakdown of cellular lipids in long-standing effusions such as rheumatoid pleuritis, tuberculosis, or myxedema and by definition the effluent contains high concentrations of cholesterol.(2) Differentiation of pseudochylothorax from chylothorax is important as their milky or opalescent appearance is similar, however therapeutic management strategies differ.


Peritoneal Fluid:

Chylous ascites is the name given to peritoneal effusions containing chylomicrons. Obstruction of lymph flow causing leakage from dilated subserosal lymphatics, exudation through the walls of retroperitoneal megalymphatics, and direct leakage of chyle due to a lymphoperitoneal fistula have been proposed as possible mechanisms causing chylous ascites.(3) Elevated triglyceride concentrations have the best correlation with detection of chylomicrons, while cholesterol is not useful at predicting the presence or absence of chylomicrons.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

An interpretive report will be provided.

Interpretation Provides information to assist in interpretation of the test results

Pleural fluid cholesterol concentrations 46 to 65 mg/dL are consistent with exudative effusions.

Cholesterol concentrations >200 mg/dL suggest pseudochylous effusion.

Triglyceride concentrations >110 mg/dL are consistent with chylous effusions.

Triglyceride concentrations <50 mg/dL are usually not due to chylous effusions.


Fluid: Peritoneal

Peritoneal fluid triglyceride concentrations >187 mg/dL are most consistent with chylous effusion.

Cholesterol concentrations 33 to 70 mg/dL suggest malignant causes of ascites.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

No significant cautionary statements

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Hooper C, Lee YC, Maskell N: BTS Pleural Guideline Group. Investigation of a unilateral pleural effusion in adults: British Thoracic Society Pleural Disease Guideline 2010. Thorax 2010;65(Suppl2):ii4-17

2. Staats BA, Eleffson RD, Budahn LL, et al: The lipoprotein profile of chylous and nonchylous pleural effusions. Mayo Clin Proc 1980;55:700-704

3. Thaler MA, Bietenbeck A, Schulz C, et al: Establishment of triglyceride cut-off values to detect chylous ascites and pleural effusions. Clin Biochem 2017;50(3) 134-138

4. Burtis CA, Ashwood ER, Bruns DE, Tietz NW: In Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Fifth edition. St. Louis, Elsevier/Saunders, 2012:1 online resource (xviii, 2238 p.)

5. Noble RP: Electrophoretic separation of plasma lipoproteins in agarose gel. J Lipid Res 1968;9:693-700

6. Sepiashvili L, Dahl AR, Meeusen JM, et al: A man with recurrent ascites after laparoscopic cholecystectomy, Clin Chem 2017;63(7):1199-1203

7. Ellefson RD, Elveback L, Weidman W: Application of methods used for lipoprotein analysis: plasma lipoproteins of children and youths in Rochester, MN. DHEW Publication No. (NIH) 1978;78-1472