Test Catalog

Test ID: LEU    
Fecal Leukocytes, Feces

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

Suggesting the presence of pathogens such as Salmonella, Shigella, and amebiasis

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

Leukocytes are not normally seen in feces in the absence of infection or other inflammatory processes. Fecal leukocytosis is a response to infection with microorganisms that invade tissue or produce toxins, which causes tissue damage.


Fecal leukocytes are commonly found in patients with shigellosis and salmonellosis and sometimes in amebiasis. Mononuclear cells are found in typhoid fever.


Ulcerative colitis may also be associated with fecal leukocytosis.

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.

Interpretive report

Interpretation Provides information to assist in interpretation of the test results

When fecal leukocytes are found they are reported in a semiquantitative manner: "few" indicates < or =2/oil immersion microscopic field (OIF); "moderate" indicates 3/OIF to 9/OIF; "many" indicates > or =10/OIF.


The greater the number of fecal leukocytes, the greater the likelihood that an invasive pathogen such as Salmonella or Shigella is present.


Few or no leukocytes and many erythrocytes suggests amebiasis.


Fecal leukocytes are rarely seen in diarrheas caused by other parasites or viruses.

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

Fecal leukocyte examinations cannot be performed on formalin-preserved specimens. Therefore, ECOFIX-preserved or polyvinyl alcohol-preserved feces must be sent to the laboratory.

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

Pickering LK, DuPont HL, Olarte J, et al: Fecal leukocytes in enteric infections. Am J Clin Pathol 1977;68:562-565