What Is Rheumatoid Factor? What This Blood Test Can Reveal About Your Autoimmune Disease

Blood tests are usually an important part of the workup for diagnosing inflammatory arthritis and other autoimmune diseases, but it’s not common that a single blood test can clinch a diagnosis. Certain blood tests detect the presence of antibodies or proteins, which can signal that your immune system is in overdrive or attacking itself. Others measure levels of inflammation in the body, which can help your doctor monitor how controlled your disease is over time.But blood tests have their limitations, so it’s important to know what any given test can — and can’t — tell you, as well as what the numbers actually mean. Here’s what you need to know about getting a blood test for rheumatoid factor.What Is Rheumatoid Factor?Rheumatoid factor (RF) is a group of antibodies that attack a person’s own tissue instead of targeting invaders, like bacteria or viruses. High concentrations of rheumatoid factor in your blood suggest to doctors that your autoimmune system is acting up. The rheumatoid fac...