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Test ID: SAM    
Entamoeba histolytica Antibody, Serum

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

As an adjunct in the diagnosis of extraintestinal amebiasis, especially liver abscess

 

Serology may be particularly useful in supporting the diagnosis of amebic liver abscess in patients without a definite history of intestinal amebiasis and who have not spent substantial periods of time in endemic areas

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

Amebiasis is an infection by the protozoan parasite, Entamoeba histolytica. The infection is acquired by ingestion of cysts in fecally contaminated food or water; excystation and infection occur in the large intestine.

 

After excystation, trophozoites attach to the intestinal wall and liberate extracellular enzymes which enable invasion of the mucosa and spread to other organs, especially the liver and lung where abscesses develop.

 

Amebiasis (or amebic dysentery) can cause bloody diarrhea accompanied by fever and prostration. Leukocytes, WBCs, and RBCs are found in the stools. Liver abscess can develop several weeks to months later producing hepatomegaly and fever.

 

Pathogenic (Entamoeba histolytica) and nonpathogenic (Entamoeba dispar) species of Entamoeba occur. Additionally, some of those infected with pathogenic strains are asymptomatic cyst carriers.

 

Intestinal amebiasis should be diagnosed by detected Entamoeba histolytica in stool specimens.

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.

Expected values: negative

Interpretation Provides information to assist in interpretation of the test results

A positive result suggests current or previous infection with Entamoeba histolytica.

 

Since pathogenic and nonpathogenic species of Entamoeba cannot be differentiated microscopically, some authorities believe a positive serology indicates the presence of the pathogenic species (ie, Entamoeba histolytica).

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

Previous episodes of intestinal amebiasis may produce a positive serology.

 

Serologic results should be used as an aid in diagnosis and should not be interpreted as diagnostic by themselves.

 

Direct detection of Entamoeba histolytica in stool specimens is recommended to diagnose intestinal amebiasis.

Clinical Reference Provides recommendations for further in-depth reading of a clinical nature

Bruckner DA: Amebiasis. Clin Microbiol Rev 1992;5:356-369