Trophozoite Antigen in Serum/Plasma (Giardia duodenalis)

Why This Test Is Done

Your healthcare provider may order this test if you have symptoms like persistent diarrhea, stomach cramps, bloating, or weight loss, especially after traveling to areas with poor sanitation. It may also be used to confirm a diagnosis if other tests are inconclusive or if you have recurrent symptoms.

What to Expect Before the Test

No special preparation is needed for this test. You may have a blood draw from a vein in your arm or a sample of bodily fluid (like saliva or stool) collected in a lab container. If a blood sample is taken, you might feel a slight pinch, but it usually doesn’t cause discomfort.

What the Test Results Mean

Positive results indicate the presence of Giardia antigens, suggesting an active infection. Negative results mean the test did not detect the parasite, but other causes of symptoms may still be possible. Follow-up testing or additional evaluation may be needed if symptoms persist.

Possible Side Effects or Risks

There are generally no serious risks with this test. Minor side effects from blood draws may include slight bruising, swelling, or a small amount of bleeding at the site. Rarely, a reaction to the needle might occur.