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Test Code LAB3310 Toxoplasma gondii Antibody, IgM and IgG, Serum

Secondary ID

39857

Useful For

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.

Profile Information

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

Method Name

Multiplex Flow Immunoassay (MFI)

Reporting Name

Toxoplasma Ab, IgM and IgG, S

Specimen Type

Serum


Specimen Required


Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Aliquot tube

Specimen Volume: 1.5 mL

Collection Instructions: Centrifuge and aliquot serum into a plastic vial.


Specimen Minimum Volume

0.8 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 14 days
  Frozen  14 days

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Heat-inactivated specimen Reject

Reference Values

Toxoplasma IgM

Negative

 

Toxoplasma IgG

Negative

 

Toxoplasma IgG Value

≤9 IU/mL (Negative)

10-11 IU/mL (Equivocal)

≥12 IU/mL (Positive)

Reference values apply to all ages.

Cautions

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

 

Sera collected 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 patients who are either HIV-positive, receiving immunosuppressive therapy, or have other disorders leading to immunosuppression.

 

Heterophile antibodies in the patient specimens 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 (07/25/1997), the US Food and Drug Administration suggests that sera found to be positive for T 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.

Day(s) Performed

Monday through Friday

Report Available

Same day/1 to 3 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

86778-Toxoplasma IgM

86777-Toxoplasma IgG

LOINC Code 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
TOXG Toxoplasma Ab, IgG, S 40677-7
TXM Toxoplasma Ab, IgM, S 40678-5
DEXG6 Toxoplasma IgG Value 8039-0

NY State Approved

Yes

Forms

If not ordering electronically, complete, print, and send Infectious Disease Serology Test Request (T916) with the specimen.

Test Classification

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.

Testing Algorithm

For more information see Meningitis/Encephalitis Panel Algorithm