The sample is sent to a lab, where it is mixed with latex beads coated with a specific antibody or antigen. If the suspected substance is present, the latex beads will clump together (agglutinate).
Latex agglutination results take about 15 minutes to an hour.
How to Prepare for the Test
Your health care provider may tell you to limit certain foods or medicines shortly before the test to ensure accurate test results.
Why the Test is Performed
This test is a quick way to determine the absence or presence of an antigen or antibody. Your provider will base any treatment decisions, at least in part, on the results of this test.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.
What Abnormal Results Mean
If there is an antigen-antibody match, agglutination will occur.
The risk level depends on the type of test.
URINE AND SALIVA TESTS
There is no risk with the urine or saliva test.
Veins and arteries vary in size from one person to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight, but may include:
Fainting or feeling lightheaded
Hematoma (blood accumulating under the skin)
Infection (a slight risk any time the skin is broken)
CEREBROSPINAL FLUID TEST
Risks of lumbar puncture include:
Bleeding into the spinal canal or around the brain (subdural hematomas)
Discomfort during the test
Headache after the test that can last a few hours or days. If headaches last more than a few days (especially when you sit, stand or walk) you might have a "CSF-leak". You should talk to your doctor if this occurs.
Hypersensitivity (allergic) reaction to the anesthetic
Infection introduced by the needle going through the skin
Ashihara Y, Kasahara Y, Nakamura RM. Immunoassays and immunochemistry. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 44.
Frank A. Greco, MD, PhD, Director, Biophysical Laboratory, Edith Nourse Rogers Memorial Hospital, Bedford, MA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.