Sign in →

Test Code TXMGP 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


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 Special Container
Serum Refrigerated (preferred) 14 days
  Frozen  14 days

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Heat-inactivated specimen Reject

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.

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.

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 T 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.

 

IgG is only indicative of previous exposure to Toxoplasma (recent or past). A single positive Toxoplasma IgG result should not be used to diagnose recent infection. Seroconversion from negative to positive IgG is indicative of recent T gondii infection.

Day(s) Performed

Monday through Saturday

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

Specimen Retention Time

14 days

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.