Are Serologic Tests?
Serologic tests are blood tests that look for antibodies in your
blood. They can involve a number of laboratory techniques. Different types of
serologic tests can diagnose various disease conditions. Serologic tests have
one thing in common. They all focus on proteins made by your immune system.
This vital body system helps keep you healthy by destroying foreign invaders
that can make you ill. The process for having the test is the same regardless
of which technique the laboratory uses during serologic testing.
Do I Need a Serologic Test?
To understand serologic tests and why they’re useful, it’s
helpful to know a little about the immune system and why we get sick.
substances that provoke a response from the immune system. They are most often
too small to see with the naked eye. They can enter the human body through the
mouth, through broken skin, or through the nasal passages. Antigens that
commonly affect people include the following:
The immune system defends against antigens by producing antibodies. These antibodies are
particles that attach to the antigens and deactivate them. When your doctor tests your blood, they can
identify the type of antibodies and antigens that are in your blood sample and
identify the type of infection you have.
Sometimes the body mistakes its own healthy tissue for outside
invaders and produces unnecessary antibodies. This is known as an autoimmune
disorder. Serologic testing can detect these antibodies to help your doctor
diagnose an autoimmune disorder.
Happens During a Serologic Test?
A blood sample is all that the laboratory needs to conduct
The test will occur in your doctor’s office. Your doctor will
insert a needle into your vein and collect blood for a sample. The doctor may
simply pierce the skin with a lancet if conducting serologic testing on a young
The testing procedure is very quick. The pain level for most
people isn’t severe. Excessive bleeding and infection may occur, but the risk
of either of these is very low.
Are the Types of Serologic Tests?
Because antibodies are so diverse, various tests are useful for
detecting the presence of different types:
- An agglutination assay shows whether antibodies
exposed to certain antigens will cause particle clumping.
- A precipitation test shows whether the antigens
are similar by measuring for the presence of antibody in body fluids.
- The Western blot test identifies the presence of
antimicrobial antibodies in your blood by their reaction with target antigens.
Do the Results Mean?
Normal Test Results
Your body produces antibodies in response to antigens. If testing
shows no antibodies, it indicates you don’t have a current or past infection.
Results that show there are no antibodies in the blood sample are normal.
Abnormal Test Results
Antibodies in the blood sample often mean you’ve had an immune
system response to a specific antigen from either a current or a past exposure
to a disease or foreign protein.
The testing may also diagnose an autoimmune disorder. In that
case, antibodies to normal or non-foreign proteins or antigens would be present
in the blood.
The presence of certain types of antibodies can also mean that you’re
immune to one or more antigen. This means that future exposure to the antigen
or antigens won’t result in illness.
Serologic testing can diagnose multiple illnesses, including:
- brucellosis, which is caused by bacteria
- amebiasis, which is caused by a parasite
- measles, which is caused by a virus
- rubella, which is caused by a virus
- fungal infections
Happens After Serologic Testing?
The care and treatment provided after serologic testing can vary.
It often depends on whether antibodies were found. It may also depend on the
nature of your immune response and its severity.
An antibiotic or another type of medication may help your body
fight the infection. Even if your results were normal, your doctor might order
an additional test if they still think you might have a specific type of
The bacteria, virus, parasite, or fungus in your body will
multiply over time. In response, your immune system will produce more
antibodies. This makes them easier to detect as time goes on and the infection
The tests results may also show the presence of antibodies
related to chronic conditions, such autoimmune disorders.
Your doctor will explain your test results and what the next
steps will be.