Toxoplasma gondii Antibody, IgM, Serum

Test Code

TOXPM

Alias/See Also

Epic: LAB659
Mayo: TXM

T. gondii
Toxoplasma gondii
Toxoplasma IgM Antibody Assay
Toxoplasmosis
Torch
TorC

CPT Codes
86778

Preferred Specimen

Specimen Type: Serum
Collection Container: Serum gel
Specimen Volume: 1 mL

Minimum Volume

0.8 mL

Instructions

Centrifuge and aliquot serum into a plastic vial.

Transport Container

Plastic vial

Specimen Stability

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

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Gross hemolysis	Reject
Gross lipemia	Reject
Heat-inactivated specimen	Reject

Methodology
Multiplex Flow Immunoassay (MFI)

Setup Schedule

Monday through Saturday

Report Available

Same day/1 to 3 days

Limitations

CAUTIONS

Diagnosis of recent infection by Toxoplasma gondii can only be established on the basis of 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 specimen was collected too soon after infection, IgM antibodies to Toxoplasma gondii may be absent. If this is suspected, a second serum specimen should be collected 2 to 3 weeks later, and the test repeated.

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.

The performance of the assay has not been established for cord blood testing.

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 US Food and Drug Administration suggests that sera found to be positive for Toxoplasma gondii IgM antibodies should be submitted to a Toxoplasma reference laboratory.

Reference Range

REFERENCE VALUES

Negative
Reference values apply to all ages.

INTERPRETATION

Active toxoplasmosis is suggested by the presence of IgM-class antibodies, but elevated anti-IgM titers may be absent in patients who are immunocompromised. 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 detection of Toxoplasma gondii DNA by polymerase chain reaction (PCR) analysis of cerebrospinal fluid or amniotic fluid specimens (PTOX / Toxoplasma gondii, Molecular Detection, PCR, Varies).

For confirmation of toxoplasmosis, the US Food and Drug Administration issued a Public Health Advisory (07/25/1997) that recommends sera found to be positive for Toxoplasma gondii IgM antibodies should be sent to a Toxoplasma reference laboratory.

A single negative result should not be used to rule-out toxoplasmosis, and repeat testing is recommended for patients at high risk for infection.

Clinical Significance

USEFUL FOR

Detecting recent infection with Toxoplasma gondii

CLINICAL INFORMATION

Toxoplasma gondii is an obligate intracellular protozoan parasite 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, T gondii can remain latent for the life of the host; the risk for reactivation is highest among individuals who are immunosuppressed.

Seroprevalence studies performed in the United States indicate approximately 6.7% of individuals between the ages of 12 and 49 have antibodies to T gondii.(2)

Infection of immunocompetent adults is typically asymptomatic. In symptomatic cases, patients most frequently 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 that are otherwise immunosuppressed. These infections are thought to be caused by reactivation of latent infections and commonly involve 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.

Performing Laboratory
Mayo Clinic Laboratories - Rochester
3050 Superior Drive NW
Rochester, MN 55901

Additional Information
Toxoplasma gondii Antibody, IgM, Serum

Last Updated: May 23, 2024
Last Review: N. Wolford, May 23, 2024

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.