Test Catalog

Test Id : GIAR

Giardia Antigen, Feces

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

Sensitive screening for the detection of Giardia antigens present in fecal specimens

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Name
A short description of the method used to perform the test

Enzyme-Linked Immunosorbent Assay (ELISA)

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Giardia Ag, F

Lists additional common names for a test, as an aid in searching


Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Specimen Type
Describes the specimen type validated for testing


Ordering Guidance

Duodenal, colonic wash, or small bowel aspirates are not acceptable for this test. If giardiasis is suspected, order OPE / Ova and Parasite, Travel History or Immunocompromised, Feces.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Submit only 1 of the following specimens:



Specimen Type: Preserved feces


-Formalin 10% Buffered Neutral 15 mL (T466)

-Stool Collection Kit, Random (T635)


Preferred: Fecal container with 10% buffered formalin preservative

Acceptable: SAF (sodium acetate formalin)

Specimen Volume: 5 grams

Specimen Stability Information: Ambient (preferred) 60 days



Specimen Type: Unpreserved feces


-Stool container, Small (Random), 4 oz (T288)

-Stool Collection Kit, Random (T635)

Container/Tube: Fecal container

Specimen Volume: 5 grams

Specimen Stability Information: Frozen 60 days

Special Instructions
Library of PDFs including pertinent information and forms related to the test


Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.

2 grams

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Grossly bloody feces (containing no visible specimen)
Very mucoid feces
Specimens preserved in ECOFIX (green cap), C and S (orange cap), or methiolate formalin (MF)
Duodenal aspirates
Small bowel aspirates

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Fecal Varies

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

Sensitive screening for the detection of Giardia antigens present in fecal specimens

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

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

Giardia duodenalis (also known as Giardia lamblia, Giardia intestinalis) is a flagellated protozoan parasite found in contaminated natural streams, lakes, and surface water municipal reservoirs. Several animals may serve as a host for G duodenalis, including dogs and beavers. Humans become infected when ingesting the environmentally resistant parasite cysts in water, food, and by the fecal-oral route (eg, on hands or fomites).


Following ingestion, each cyst releases two trophozoites, which infect the small intestine by attaching to the mucosa with a ventral sucking disc. Infection may be associated with a variety of outcomes ranging from asymptomatic disease (estimated to occur in 50% of infected individuals) to acute and chronic giardiasis. When present, symptoms generally appear 7 to 14 days after infection and consist of watery diarrhea, malaise, malodorous steatorrhea, flatulence, abdominal cramping, nausea or vomiting, weight loss, and low-grade fever. Less commonly, patients experience constipation and urticaria. Symptoms will resolve in most patients after a period of several weeks. However, approximately 15% to 20% will remain chronically infected without treatment and experience ongoing loose stools, weight loss, malabsorption, steatorrhea, abdominal cramping, flatulence, and burping. Longstanding malabsorption may result in vitamin deficiencies and hypoalbuminemia. Acquired lactose intolerance may also occur and persist for months after successful parasite eradication.


Giardiasis is the most common intestinal parasitic infection in the United States reported to the Centers for Disease Control and Prevention and is a common cause of diarrhea in children (especially in daycare centers), travelers, and campers or hikers. It is also responsible for waterborne epidemics. Although Giardia parasites (cysts and trophozoites) may be seen using the microscopy-based stool parasitic exam (OPE / Ova and Parasite, Travel History or Immunocompromised, Feces), this is an insensitive method for detection and requires examination of three or more specimens. Instead, detection of parasite antigen or DNA is recommended for optimal sensitivity. The Giardia antigen test is ideal for settings in which giardiasis is specifically suspected (eg, outbreak scenarios), whereas the multiplex gastrointestinal polymerase chain reaction panel (GIP / Gastrointestinal Pathogen Panel, PCR, Feces) is better suited for evaluating multiple potential causes of diarrhea, including parasitic, viral, and bacterial pathogens.


For more information about diagnostic tests that may be of value in evaluating patients with diarrhea see the following:


-Parasitic Investigation of Stool Specimens Algorithm

-Laboratory Testing for Infectious Causes of Diarrhea

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.


Provides information to assist in interpretation of the test results

A positive enzyme-linked immunosorbent assay indicates the presence in a fecal specimen of Giardia antigens.


Interpretation of results should be correlated with patient symptoms and clinical picture.

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

Small numbers of organisms residing only in the duodenum may not yield a positive test result.


Giardia antigen detection should be used as an aid in diagnosis of giardiasis. A single diagnostic assay should not be used as the only criteria to form a clinical conclusion.


Testing of at least 2 consecutive fecal specimens by enzyme-linked immunosorbent assay is recommended before considering the results negative.


Feces containing large amounts of leukocytes or red blood cells may give false-positive results.

Supportive Data

As per the manufacturer, the assay has a sensitivity of 96%, specificity of 97%, and a positive predictive value of 95%.

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

1. Garcia LS, Arrowood M, Kokoskin E, et al. Practical guidance for clinical microbiology laboratories: Laboratory diagnosis of parasites from the gastrointestinal tract. Clin Microbiol Rev. 2017;31(1):e00025-17

2. Hanson KL, Cartwright CP. Use of an enzyme immunoassay does not eliminate the need to analyze multiple stool specimens for sensitive detection of Giardia lamblia. J Clin Microbiol. 2001;39(2):474-477

3. Centers for Disease Control and Prevention (CDC) National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of Foodborne, Waterborne, and Environmental Diseases (DFWED): Parasites-Giardia. CDC; Updated May 19, 2022. Accessed August 28, 2023. Available at www.cdc.gov/parasites/giardia/index.html

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Description
Describes how the test is performed and provides a method-specific reference

Giardia antigens present in the stool supernatant are captured by antibodies coating the wells of a microtiter plate. The bound antigen is sandwiched by the addition of a second antibody, and the signal is amplified by adding biotin-streptavidin horseradish peroxidase. Blue color develops with the presence of bound antigen. The reaction is stopped with the addition of acid and read visually or with the aid of a spectrophotometer.(Rosenblatt JE, Sloan LM, Schneider SK. Evaluation of an enzyme-linked immunosorbent assay for the detection of Giardia lamblia in stool specimens. Diagn Microbiol Infect Dis. 1993;16(4):337-341; package insert: ProSpecT Giardia Microplate Assay. Oxoid; 03/2012)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday, Wednesday, Friday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

1 to 3 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

Fresh/Frozen: 1 week; Preserved specimens: 1 week

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

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  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their account representative. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.


LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
GIAR Giardia Ag, F 6412-1
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
24085 Giardia Ag, F 6412-1

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports