What 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.


Why 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. Antigens are 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.


What happens during a serologic test?


A blood sample is all that the laboratory needs to conduct serologic testing. 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 child. The testing procedure is quick. The pain level for most people isn’t severe. Excessive bleeding and infection may occur, but the risk of either of these is low.


What are the types of serologic tests?


Antibodies are diverse. So, there are various tests for detecting the presence of different types of antibodies. These include:


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.


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