Latex agglutination test

Definition

The latex agglutination test is a laboratory method to check for certain antibodies or antigens in a variety of body fluids including saliva, urine, cerebrospinal fluid, or blood.

How the Test is Performed

The test depends on what type of sample is needed.

• Saliva
• Urine
• Blood
• Cerebrospinal fluid (lumbar puncture)

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. Follow instructions on how to prepare for the test.

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 Results

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.

Risks

The risk level depends on the type of test.

URINE AND SALIVA TESTS

There is no risk with the urine or saliva test.

BLOOD 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:

• Excessive bleeding
• 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

References

Aoyagi K, Ashihara Y, Kasahara Y. Immunoassays and immunochemistry. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 44.