Laboratory Services

Toxoplasma gondii Antibody, IgM and IgG (Separate Determinations), Serum

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Updated Test Information:

Test Description
Toxoplasma gondii Antibody, IgM and IgG (Separate Determinations), Serum
Synonym(s)

T. gondii; Toxoplasma gondii; Toxoplasma IgG & IgM Antibody Assays; Toxoplasma, IgG Antibody, Serum; Toxoplasma, IgM Antibody, Serum; Toxoplasmosis

Test ID
TXMGP
General Information

Useful for:



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

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

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



Specimen Type

Serum

Specimen Requirements

  • Preferred: Serum Gel (SST)

  • Acceptable: Red Top

Stability

  • Refrigerated (preferred): 14 days

  • Frozen: 14 days

Unacceptable Specimen Conditions

  • Gross hemolysis

  • Gross lipemia

  • Heat-inactivated specimen

Limitations

  • 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

    • 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



Methodology

Multiplex Flow Immunoassay (MFI)

Estimated TAT

1-3 days

Testing Schedule

Monday-Friday

Test Includes

  • TXM: Toxoplasma Ab, IgM

  • TOXGP: Toxoplasma Ab, IgG

Retention

14 days

CPT Code(s)

86777; 86778

Additional Information
Minimum Sample Volume

1.2 mL

Reference Range
  • Toxoplasma IgM
    • Negative
  • Toxoplasma IgG
    • Negative (≤ 9 IU/mL)
Performing Lab

Mayo

LOINC Code(s)

40677-7, 40678-5, 8039-0