I have a question on diagnosing Lupus/Rheumatoid Arthritis. I went to the doctor with several symptoms, and of course, questions. I have tested positive for the RA or ANA factor in an Arthritis Panel. However, all blood tests after that have turned up completely normal. My rheumatologist believes that I have recently had a "flare-up", and believes that I have either RA or Lupus. I was treated with prednisone, and it helped greatly. Is it possible to have one of these diseases without a positive blood test? If so, how long does the disease take to show up? My doctor wants to treat me-but how is this possible without a confirmed diagnosis? Please help me out. I am so confused.