Hi travlr!
I'm not an expert and by all means call your doctor or a med service that can answer this question much better than I can. One of the hospitals here has an "ask a nurse" call in number. You just call them up and ask them questions. They can tell you if you need to see a doc for more info, but on most questions they provide some pretty darn solid information.
Anyway, as I understand it, the ana test numbers depend on what type of test it is and how the numbers are reported. I'd just encourage you to call your doc and talk to him/her or whichever nurse in the office is most likely to answer your question thoroughly and patiently. Sometimes I feel like i'm beating this one nurse over the head to get any info. Ignorance is not bliss and it's my test, so please explain it without making me feel like a goober!!!
Ana is a pretty important number in helping to diagnose lupus, but there is no one test that determines the diagnosis. It's just an important test on the way to finding an answer. Keep plugging away!
Good luck!!