When an infection is suspected, a physician may order a serologic test to examine antibodies in a sample to determine how the body is reacting to bacteria, viruses, and other foreign substances it does not recognize. Produced by the immune system, these Y-shaped proteins help the body fight infections. Understanding the types of antibodies being produced offers a clue as to what type of invader the body’s immune system is fighting. A blood sample is all that’s needed to conduct serologic testing.
Why Serologic Testing is Needed
A serology test is usually recommended if a patient is showing signs of some type of infection. The immune system goes into action when it is “attacked’ by foreign invaders called antigens, or substances that trigger an immune system response. Bacteria, fungi, viruses, and parasites are the most common types of antigens, or foreign invaders, that may cause the immune system to produce antibodies.
What the Testing Shows
Antibodies attach themselves to antigens in an attempt to deactivate them. What a serologic test will do is identify the type of antibodies being produced by the body to determine what specific type of infection is causing the problem. In some cases, the body mistakenly attaches its own tissues. If this happens, a patient has what’s termed an autoimmune disease or disorder. Conditions of this nature include:
- Rheumatoid and reactive arthritis
- Celiac disease
- Scleroderma (connective tissue disease)
- Inflammatory bowel diseases
- Graves’ disease
- Type 1 diabetes
A blood sample will be collected to do a serologic test. If a child is being tested, a lancet may be used to obtain a blood sample in a way that’s more comfortable. The sample will then be properly sealed and labeled and sent to our laboratory for analysis.
Types of Tests
Different types of testing will be done to identify the type of antibodies being produced. Common serologic tests include:
- Agglutination Assays – Quick and easy, this type of test determines whether or not particle clumping will occur when antibodies exposed to antigens. An agglutination assay is the type of test that can identify the rheumatoid factor (RF) to indicate if a patient has this form of arthritis.
- Precipitation Testing – The presence of antibodies in body fluids is measured with this type of test. A precipitation test shows whether or not the antigens are similar.
- Western Blot Testing – Antimicrobial antibodies can be detected with this serologic test based on how they react to specific antigens. A western blot test is often a follow-up test done to help diagnose conditions such as HIV or Lyme disease.
Results are considered normal if there are no antibodies present in a blood sample, meaning the patient has no infection. When antibodies are present in a sample, results are considered abnormal and a patient has an infection. The presence of certain antibodies may also indicate that a patient is immune to certain antigens. Serologic testing is used to diagnose several conditions, including:
- Brucellosis (a bacterial infection usually caused by under-cooked meat)
- Measles and rubella
- Various fungal infections
Make well-informed treatment decisions with our prompt, accurate serology testing. Available within 24 hours for most tests, results are presented in a clear, concise report. Having easy access to results online means the right treatment can be recommended to avoid the unnecessary use of antibiotics and prevent an infection from spreading.