Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Leukocytes are not normally seen in stools 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 (erythrocytes) and sometimes in amebiasis. Mononuclear cells are found in typhoid fever.
Ulcerative colitis may also be associated with fecal leukocytosis.
Suggesting presence of pathogens such as Salmonella, Shigella, and amebiasis
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 leukocytes, the greater the likelihood that an invasive pathogen is present. The finding of many fecal leukocytes is a good indicator of the presence of an invasive microbiological pathogen such as Salmonella or Shigella.
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, fresh, ECOFIX-preserved, or polyvinyl alcohol-preserved stool must be sent to the laboratory.
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.
Clinical References Provides recommendations for further 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