Test Catalog

Test Id : TXMGP

Toxoplasma gondii Antibody, IgM and IgG, Serum

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

Determining whether a patient has had previous exposure to or recent infection with Toxoplasma gondii

 

IgG is not useful for diagnosing infection in infants younger than 6 months of age. IgG antibodies in this age group usually are the result of passive transfer from the mother.

Highlights

Detection of IgM-class antibodies to Toxoplasma gondii may be useful as a screen for recent infection with Toxoplasma gondii.

 

Per the FDA, IgM-positive results by a screening assay should be confirmed, for example by a Toxoplasma reference laboratory.

 

A single negative result by this assay does not rule-out toxoplasmosis as the specimen may have been collected too early following infection, prior to development of detectable antibodies.

 

A single IgG-positive result is indicative of exposure to Toxoplasma gondii at some time in the past.

Profile Information
A profile is a group of laboratory tests that are ordered and performed together under a single Mayo Test ID. Profile information lists the test performed, inclusive of the test fee, when a profile is ordered and includes reporting names and individual availability.

Test Id Reporting Name Available Separately Always Performed
TXM Toxoplasma Ab, IgM, S Yes Yes
TOXGP Toxoplasma Ab, IgG, S Yes Yes

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

See Meningitis/Encephalitis Panel Algorithm in Special Instructions.

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

Multiplex Flow Immunoassay (MFI)

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

Yes

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

Toxoplasma Ab, IgM and IgG, S

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

T. gondii

Toxoplasma gondii

Toxoplasma IgG & IgM Antibody Assays

Toxoplasma, IgG Antibody, Serum

Toxoplasma, IgM Antibody, Serum

Toxoplasmosis

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

See Meningitis/Encephalitis Panel Algorithm in Special Instructions.

Specimen Type
Describes the specimen type validated for testing

Serum

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

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Aliquot tube

Specimen Volume: 1.5 mL

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

Forms

If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

1.2 mL

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

Gross hemolysis Reject
Gross lipemia Reject
Heat-inactivated specimen Reject

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
Serum Refrigerated (preferred) 14 days
Frozen 14 days

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

Determining whether a patient has had previous exposure to or recent infection with Toxoplasma gondii

 

IgG is not useful for diagnosing infection in infants younger than 6 months of age. IgG antibodies in this age group usually are the result of passive transfer from the mother.

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

See Meningitis/Encephalitis Panel Algorithm in Special Instructions.

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

Toxoplasma gondii is an obligate intracellular protozoan parasite that is capable of infecting a variety of intermediate hosts including humans. Infected definitive hosts (cats) shed oocysts in feces that rapidly mature in the soil and become infectious. Toxoplasmosis is acquired by humans through ingestion of food or water contaminated with cat feces or through eating undercooked meat containing viable oocysts. Vertical transmission of the parasite through the placenta can also occur, leading to congenital toxoplasmosis. Following primary infection, T gondii can remain latent for the life of the host; the risk for reactivation is highest among immunosuppressed individuals.

 

Seroprevalence studies performed in the United States indicate that approximately 6.7% of individuals between the ages of 12 and 49 have antibodies to T gondii.

 

Infection of immunocompetent adults is typically asymptomatic. In symptomatic cases, patients most commonly present with lymphadenopathy and other nonspecific constitutional symptoms, making definitive diagnosis difficult to determine.

 

Severe-to-fatal infections can occur among patients with AIDS or individuals who are otherwise immunosuppressed. These infections are thought to be caused by reactivation of latent infections and commonly involved the central nervous system.

 

Transplacental transmission of the parasites resulting in congenital toxoplasmosis can occur during the acute phase of acquired maternal infection. The risk of fetal infection is a function of the time at which acute maternal infection occurs during gestation. The incidence of congenital toxoplasmosis increases as pregnancy progresses; conversely, the severity of congenital toxoplasmosis is greatest when maternal infection is acquired early during pregnancy. A majority of infants infected in utero are asymptomatic at birth, particularly if maternal infection occurs during the third trimester, with sequelae appearing later in life. Congenital toxoplasmosis results in severe generalized or neurologic disease in about 20% to 30% of the infants infected in utero; approximately 10% exhibit ocular involvement only and the remainder are asymptomatic at birth. Subclinical infection may result in premature delivery and subsequent neurologic, intellectual, and audiologic defects.

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.

Toxoplasma IgM

Negative

 

Toxoplasma IgG

Negative

 

Toxoplasma IgG Value

< or =9 IU/mL (Negative)

10-11 IU/mL (Equivocal)

> or =12 IU/mL (Positive)

Reference values apply to all ages.

Interpretation
Provides information to assist in interpretation of the test results

Active toxoplasmosis is suggested by the presence of IgM-class antibodies, but elevated anti-IgM titers may be absent in immunocompromised patients. In addition, elevated IgM can persist from an acute infection that may have occurred as long ago as 1 year. A suspected diagnosis of acute toxoplasmosis should be confirmed by detection of Toxoplasma gondii DNA by polymerase chain reaction (PCR) analysis of cerebrospinal fluid or amniotic fluid specimens (PTOX / Toxoplasma gondii, Molecular Detection, PCR, Varies).

 

For confirmation of toxoplasmosis, the FDA issued a Public Health Advisory (07/25/1997) that recommends that sera found to be positive for T gondii IgM antibodies should be sent to a Toxoplasma reference laboratory.

 

A single negative result should not be used to rule-out toxoplasmosis and repeat testing is recommended for patients at high risk for infection.

 

IgG is only indicative of previous exposure to Toxoplasma (recent or past). A single positive Toxoplasma IgG result should not be used to diagnose recent infection. Seroconversion from negative to positive IgG is indicative of recent T gondii infection.

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

Diagnosis of recent infection by Toxoplasma gondii can only be established by a combination of clinical and serological data.

 

The result of a single serum sample does not constitute sufficient proof for diagnosis of recent infection. If a serum sample was collected too soon after infection, IgM antibodies to T gondii may be absent. If this is suspected, a second serum sample should be collected 2 to 3 weeks later and the test repeated.

 

Sera drawn very early during the acute stage of infection may have Toxoplasma IgG levels below 9 IU/mL. The Toxoplasma IgG assay should not be used alone to diagnose recent T gondii infection. Results should be considered in conjunction with clinical presentation, patient history, and other laboratory findings.

 

Results should be interpreted with caution in HIV-positive patients, patients receiving immunosuppressive therapy, or individuals with other disorders leading to immunosuppression.

 

Heterophile antibodies in the patient samples may interfere with the assay performance.

 

As with any low prevalence analyte, there is the increased possibility that a positive result may actually be false, reducing the assay's positive predictive value. Per the Public Health Advisory (7/25/1997), the FDA suggests that sera found to be positive for Toxoplasma gondii IgM antibodies should be submitted to a Toxoplasma reference laboratory.

 

The performance characteristics of this assay have not been evaluated in immunocompromised individuals and have not been established for cord blood or for testing of neonates.

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

1. Tenter AM, Heckeroth AR, Weiss LM: Toxoplasma gondii: from animals to humans. Int J Parasitol. 2000;30(12-13):1217-1258

2. Jones JL, Kruszon-Moran D, Rivera HN, et al: Toxoplasma gondii seroprevalence in the United States 2009-2010 and comparison with the past two decades. Am J Trop Med Hyg. 2014;90(6):1135-1139

3. Wang ZD, Liu, HH, Ma ZX, et al: Toxoplasma gondii infection in immunocompromised patients: A systematic review and Meta-Analysis. Front Microbiol. 2017;8:389

4. Wong SY, Remington JS: Toxoplasmosis in pregnancy. Clin Infect Dis. 1994;18(6):853-861

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

The BioPlex 2200 Toxoplasma gondii IgM and IgG assays use multiplex flow immunoassay technology. Briefly, Toxoplasma antigen-coated fluorescent beads are mixed with an aliquot of patient sample and sample diluted and incubated at 37 degrees C. During this time, IgM and IgG anti-Toxoplasma antibodies in the specimen will bind to the Toxoplasma antigen on the beads. After a wash cycle, a fluorescently labeled antihuman IgM- and IgG-antibody conjugate is added to the mixture and incubated at 37 degrees C. Following a wash step to remove unbound conjugate, the bead mixture is passed through a detector that identifies the bead based on dye fluorescence and determines the amount of antibody captured by the antigen based on fluorescence of the antihuman-IgG conjugate. Raw data is calculated in relative fluorescence intensity and is converted to an antibody index for interpretation for IgM and an IU/mL for IgG.

 

For IgM, antibody index (AI) values of 0.8 and below are considered negative. AI values of 0.9 and 1.0 are equivocal. AI values of 1.1 and above are considered positive.

 

For IgG, IU/mL values of 9 and below are considered negative. IU/mL values of 10 and 11 are equivocal. IU/mL values of 12 and above are considered positive.

Three additional dyed beads: an internal standard bead, a serum verification bead, and a reagent black bead are present in each reaction mixture to verify detector response, the addition of serum to the reaction vessel and the absence of significant nonspecific binding in serum, respectively.(Package inserts: BioPlex 2200 System, ToRC IgG and ToRC IgM. Bio-Rad Laboratories; 08/2017)

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

No

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 through Saturday

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.

Same day/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

14 days

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

Rochester

Fees
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.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. 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.

86778-Toxoplasma IgM

86777-Toxoplasma IgG

LOINC® Information

Test Id Test Order Name Order LOINC Value
TXMGP Toxoplasma Ab, IgM and IgG, S 88746-3
Result Id Test Result Name Result LOINC Value
Result LOINC Value Tooltip

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