Is there a blood test for lupus?

Yes: There is a simple blood test for lupus called an "ana" (for antinuclear antibody). It is positive, or detectable, in about 20% of healthy people, so it is only helpful as an initial screening. A doctor can ask questions, perform a physical exam and order further tests to figure out if a positive test indicates lupus. A negative test is very reassuring.

No: There are blood tests that can suggest a diagnosis of systemic lupus erythematosus but a diagnosis is not made on blood tests alone. Frequently doctors and patients refer to the ANA as a test for lupus but more people have a positive ANA that don't have lupus than do have lupus an other diseases can cause a positive ana, like hypothyroidism.