The presence of antinuclear antibodies (ANA) in the blood is the biggest indicator of lupus. ANA tests measure the presence of antibodies that are directed against the body's cells, a sign of an autoimmune disease. While not everyone with ANA will have lupus, a positive test result is often a strong indication of the disease.
Other lab tests, such as those that check for other autoantibodies, blood cell count, and inflammation levels, may also be used to confirm a diagnosis of lupus.
However, it's crucial to note that lupus is a complex condition, and many people with ANA don't have lupus. A diagnosis is made based on a combination of factors, including symptoms, lab results, and clinical history.
