I am not diagnosed yet either. My ANA just came back at 1:320. As far as I know it is very rare for a false positive. I would think that with an ANA of 1:640 there is definitely something going on. Did they say what the pattern was? Mine is speckled which indicates lupus, mixed connective tissue disease, scleroderma or Sjogrens Syndrome. I have the butterfly rash on my face so I am thinking it is definitely lupus. I hope you feel better soon and get those results back quickly!