ANA tests identify autoantibodies in the body. And, they are one of the tools that clinicians use to help diagnose lupus.
Rheumatologists review laboratory tests, symptom logs, and family history before making a lupus diagnosis. This can be a long and challenging process. ANA tests are a crucial element as they offer insight into the functioning of the immune system by measuring the presence of particular proteins in the blood.
The newest criteria for determining a lupus diagnosis was established by the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR) in 2018. The first requirement of the criteria to be diagnosed is:
- Positive ANA test with a titer of at least 80
The titer value relates to the ratio of blood serum being tested to a dilution agent. So, a titer of 80 would mean that for every 80 parts of dilution, there was one part of blood serum. The higher the dilution, the more antibodies would need to be in the blood sample to return a positive result for the test.