Physicians have to gather information from a variety of sources: past medical history, lab tests and current symptoms. They use a list of 11 criteria to help diagnose SLE. A person needs to satisfy at least 4 out of the 11 criteria before the diagnosis can be pinpointed. Some criteria, such as a biopsy diagnosis of kidney lupus, can carry more weight.

Of the 11 criteria, 7 relate to symptoms, and 4 have to do with lab tests. The ANA test is used as a screening test for systemic lupus. We know that 95 % of people with SLE have a positive ANA. Therefore, if a person has many symptoms of systemic lupus and their ANA test is negative, that's generally regarded as pretty good evidence against lupus being the explanation for the symptoms they are having.