Toxoplasma gondii Antibody, IgM, Serum
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Aids in the diagnosis of both congenital and acute acquired toxoplasmosis
Enzyme-Linked Fluorescence Assay (ELFA)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Toxoplasma Ab, IgM, S
Toxoplasma IgM Antibody Assay
Torch -> if pt is
Toxoplasma IgM Antibody Assay
Torch -> if pt is
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Preferred: Red top
Acceptable: Serum gel
Specimen Volume: 0.5 mL
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Mild OK; Gross reject
Mild OK; Gross reject
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
|Serum||Refrigerated (preferred)||14 days|
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.(1) 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, Toxoplasma 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 9% to 11% of individuals between the ages of 6 and 49 have antibodies to Toxoplasma gondii.(2)
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.(3)
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.(4) 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 ANTIBODY, IgM
Toxoplasma IgM VALUE
0.55 to <0.65 (Equivocal)
> or =0.65 (Positive)
Active toxoplasmosis is suggested by the presence of IgM antibodies, but elevated anti-IgM titers are often 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 further testing at a toxoplasmosis reference laboratory or by detection of Toxoplasma gondii DNA by PCR analysis of cerebrospinal fluid or amniotic fluid specimens (PTOX / Toxoplasma gondii, Molecular Detection, PCR).
For confirmation of a diagnosis, the FDA issued a Public Health Advisory (7/25/1997) suggesting that sera found to be positive/equivocal for Toxoplasma gondii IgM antibody be sent to a Toxoplasma reference laboratory; CDC or Jack Remington, MD, Palo Alto Medical Foundation, 860 Bryant Street, Palo Alto, CA 94301, were recommended.(Reviewed 12/2011)
Specimens interpreted as equivocal may contain very low levels of IgM. A second specimen should be drawn and tested.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Negative results do not preclude recent primary Toxoplasma gondii infection. A negative result could indicate either no previous exposure or also could be seen in cases of remote exposure with subsequent loss of detectable antibody. A second specimen drawn at a later point in time may be needed to rule out a recent infection.
Positive serologic results alone are not diagnostic of Toxoplasma gondii infection. For example, infections with Epstein-Barr virus (EBV) have been suspected to elicit antigen-specific IgM responses (eg, false-positive IgM Toxoplasma reactions) in individuals previously sensitized to a variety of non-EBV infectious agents.
Since persisting IgM levels may be detected long after the onset of acquired infection, the use of a single serological test result must be used with caution in those cases when it is critical to establish the time of infection. This applies to the diagnosis of acute Toxoplasma gondii infection acquired during pregnancy. Determination of the date of infection based solely on the results of detectable IgM antibody to Toxoplasma gondii is not recommended. That determination should include clinical history and previous serology, since low levels of IgM antibody may persist for a year or more. The use of a test to determine a rise in IgG antibody to Toxoplasma gondii (TOXGP / Toxoplasma gondii Antibody, IgG, Serum or TOXOP / Toxoplasma gondii Antibody, IgM and IgG [Separate Determinations], Serum) may provide additional information as to the date of infection. Therefore, the FDA has instructed commercial suppliers of Toxoplasma IgM kits to recommend Toxoplasma IgG testing also be performed.
The VIDAS TOXO IgM system was compared to an indirect immunofluorescence (IFA) IgM assay (GenBio, San Diego, CA). Of 125 specimens tested, 45 and 47 were IFA- and VIDAS-positive, respectively. Using the IFA IgM as the gold standard, the sensitivity and specificity of the VIDAS Toxo IgM assay was 98% and 96%, respectively.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Luft BJ, Remington JS: Toxoplasmic encephalitis in AIDS. Clin Infect Dis 1992 August;15(2):211-222
2. Wong SY, Remington JS: Toxoplasmosis in pregnancy. Clin Infect Dis 1994 June;18(6):853-862
Method Description Describes how the test is performed and provides a method-specific reference
The VIDAS TOXO IgM system (bioMerieux Inc, Durham, NC) is an automated serologic test for use on the VIDAS analyzer, which employs the enzyme-linked fluorescence assay (ELFA) technique. The assay uses a 2-step EIA sandwich method. A pipette tip-like device, the Solid Phase Receptacle (SPR), is coated with goat anti-IgM antibodies and serves as the solid phase as well as the pipettor for the assay. The sample is diluted and cycled in and out of the SPR. Subsequently Toxoplasma gondii antigen, followed by mouse anti-Toxoplasma gondii antigen-conjugated antibodies are cycled through the SPR. A fluorescent substrate, 4-methylumbelliferyl phosphate, is added to the SPR, which catalyzes the conversion of the conjugated substrate to a fluorescent product. The intensity of the fluorescence is measured by the optical scanner of the instrument.(Package insert: VIDAS TOXO IgM, BioMerieux, Durham, NC)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Saturday, Varies
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Same day/1 day
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
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's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
This test has been cleared or approved by the U.S. 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 Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
|Result ID||Reporting Name||LOINC Code|
|TOXM||Toxoplasma Ab, IgM, S||5390-0|
|DEXM7||Toxoplasma IgM Value||40697-5|