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Test Code TOXOPL GRP Toxoplasma gondii Antibody, IgM and IgG (Separate Determinations), Serum

Useful For

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

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

TXM: Enzyme Immunoassay (EIA)

TOXGP: Multiplex Flow Immunoassay (MFI)

Reporting Name

Toxoplasma Ab, IgM and IgG, S
Seattle Children's Hospital Note:

Clinical System Name: Toxoplasma Serology IgG + IgM

Specimen Type


Specimen Required


Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 1.5 mL

Specimen Minimum Volume

1.2 mL

Specimen Stability Information

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

Reject Due To


Mild OK; Gross reject


Mild OK; Gross reject




Heat-inactivated specimen

Reference Values

Toxoplasma IgM



Toxoplasma IgG



Toxoplasma IgG Value

≤9 IU/mL (Negative)

10-11 IU/mL (Equivocal)

≥12 IU/mL (Positive)

Method Description


The Platelia Toxo IgM EIA utilizes an immunoenzymatic double sandwich method. Diluted samples and controls are placed into microplate wells coated with antibodies to human IgM. The IgM antibodies present in the samples are captured by the solid phase. Remaining antibodies (including any of the IgG class) and other serum proteins are removed by washing. A solution containing Toxoplasma gondii antigen and conjugate (monoclonal antibody to Toxoplasma gondii labeled with horseradish peroxidase) is placed into each well. Toxoplasma gondii IgM antibodies in the sample that are captured on the solid phase bind the Toxoplasma gondii antigen-conjugate complex. Excess Toxoplasma gondii antigen and conjugate are removed by washing. A chromogen solution is added that reacts with the conjugate to initiate a color development reaction. This reaction is stopped by the addition of an acid. The optical density readings for the samples are obtained with a spectrophotometer set at a wavelength of 450 nm. The presence of Toxoplasma gondii IgM antibodies in an individual sample is determined by comparing the optical density reading for the sample to the optical density reading of the calibrator serum.(Package insert: Platelia Toxo IgM EIA, Bio-Rad, Redmond, WA)



The BioPlex 2200 Toxoplasma IgG assays uses multiplex flow immunoassay technology. Briefly, Toxoplasma antigen-coated fluorescent beads are mixed with an aliquot of patient sample and sample diluent and incubated at 37° C. During this time IgG anti-Toxoplasma antibodies in the specimen will bind to the Toxoplasma antigen on the beads. After a wash cycle, a fluorescently labeled antihuman IgG-antibody conjugate is added to the mixture and incubated at 37° 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 (AI) for interpretation.  


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 insert: BioPlex 2200 System, ToRC IgG, Bio-Rad Laboratories, Clinical Diagnostics Group, Hercules, CA)

Day(s) and Time(s) Performed

Monday through Friday, 9 a.m.

Seattle Children's Hospital Note:

TAT: 3 - 5 days

Performing Laboratory

Mayo Medical 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 5388-4