ARUP's Laboratory Test Directory

0050557: Toxoplasma gondii Antibody, IgM

Test Mnemonic: TOXEIGM
Methodology: Chemiluminescent Immunoassay

Performed: Sun-Sat

Reported: Within 24 hours

Specimen Required:  
Collect: One 4 mL SST.

Transport: 1 mL serum at 2-8°C. (Min: 0.5 mL) Submit specimen in an ARUP Standard Transport Tube.

Pediatric Collection/Transport: 0.5 mL serum at 2-8°C.

Remarks: Allow serum to clot completely at room temperature.  Separate serum from cells ASAP. Acute and convalescent specimens must be labeled as such; parallel testing is preferred and convalescent specimens must be received within 30 days from receipt of the acute specimens. Please mark specimen plainly as "acute" or "convalescent."

Unacceptable Conditions: Grossly hemolyzed, contaminated or heat-inactivated specimens.

Stability: After separation from cells: Ambient: 2 days; Refrigerated: 2 weeks; Frozen: 1 year (avoid repeated freeze/thaw cycles)

Reference Interval:
0.89 IV or less: Negative - No clinically significant level of Toxoplasma gondii IgM antibody detected.
0.90-1.09 IV: Equivocal - Repeat testing in 10-14 days may be helpful.
1.10 IV or greater: Positive - Significant level of Toxoplasma gondii IgM antibody detected and may indicate a current or recent infection. However, low levels of IgM antibodies may occasionally persist for more than 12 months post-infection.

Interpretive Data:
This test is performed using the Siemens Immulite 2000 chemiluminescent immunoassay. As suggested by the CDC, any equivocal or positive result should be retested using a different assay from another reference laboratory specializing in toxoplasmosis testing, such as Palo Alto Medical Foundation (Remington). The IgG Dye test, IgM ELISA, and reflex to Avidity and/or other tests as indicated should be ordered. In addition, a convalescent sample should be drawn for comparison. Caution should be exercised in the use of IgM antibody levels in prenatal screening. Any positive results in pregnant patients, that are confirmed positive by a second reference laboratory, should be evaluated by amniocentesis and PCR testing for Toxoplasma gondii.

For male patients with equivocal or positive results, PCR may also be useful if a specimen can be collected from an affected body site.



CPT Code(s):
86778