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A titer of 1 to 8 (1:8) means that antibodies can be found when 1 part of the blood sample is diluted by up to 8 parts of a saltwater solution (saline). A larger second number means there are more antibodies in the blood. So a titer of 1 to 128 means there are more toxoplasmosis antibodies in the blood than a titer of 1 to 32.

The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range that your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

Normal results 1
Antibody Titer

IgM in babies:

Undetectable

IgM in adults:

Less than 1:64

IgG:

Less than 1:1024

Toxoplasmosis antibodies usually form within 2 weeks after being infected. The titer is the highest 1 to 2 months after infection.

  • If high titers of the IgM type of antibody are found, it means the infection is recent. If high titers of the IgG type of antibody are present, it means an infection occurred in the past.
  • Blood samples may be taken over several weeks to see if the number of antibodies is getting higher. This would mean the infection is recent.
  • Low titers that do not get higher usually mean the infection occurred in the past. After you have had toxoplasmosis, you cannot be infected again.

What Affects the Test

Other infections can cause a false-positive result in a newborn.

Other antibodies, such as rheumatoid factor or antinuclear antibodies, may also cause a false-positive result.

What To Think About

  • If your baby has the IgG antibody, he or she is not infected. If your baby has the IgM antibody, he or she does have toxoplasmosis.
  • Your newborn baby may be given a TORCH test at the same time as a toxoplasmosis test. TORCH stands for Toxoplasmosis, Other, Rubella, Cytomegalovirus, and Herpes. The TORCH test checks to see if your baby has any of these infections.
  • The toxoplasmosis polymerase chain reaction (PCR) test checks your amniotic fluid to see if toxoplasmosis is present. This test may be more accurate than other tests in finding an infection in your growing baby (fetus).

To learn more about toxoplasmosis infection in pregnancy, see the topic Toxoplasmosis During Pregnancy.

By Healthwise Staff See additional information
Primary Medical Reviewer Sarah Marshall, MD - Family Medicine
Specialist Medical Reviewer Kirtly Jones, MD - Obstetrics and Gynecology
Current as of May 29, 2013

WebMD Medical Reference from Healthwise

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