The most common blood test for SLE is the antinuclear antibodies (ANA) test, which is positive in the majority of people with SLE. However, this test can be positive for a number of reasons outside of SLE, such as when someone has a different autoimmune disease (like rheumatoid arthritis) or even when someone is completely healthy and has no disease at all (considered a false positive). This is one reason why it is important to work with a trusted medical provider for an SLE diagnosis.[1] Other antibody blood tests that are often used in the diagnosis of lupus include anti-dsDNA (anti-double-stranded DNA), anti-Sm (anti-Smith), and antiphospholipid antibodies.