Nope, there is not a single diagnostic test that clearly says "Lupus". Instead most auto-immune diseases are diagnosed by a collection of symptoms.
For Lupus, generally diagnosis is made by having 4 of 11 symptoms, where ANA may or may not be one of them. Here is a relevant discussion. www.health.com/health/gallery/0,,20468402,00.html
Lupus is diagnosed by a rheumatologist... one way to make sure your rheumy is well-versed in Lupus is to find your local chapter of www.lupus.org
and see what local Drs are active on their advisory board.
Often a Lupus diagnosis takes a long time and is partially a diagnosis of exclusion. It is more important that your symptoms are treated than it is to get a diagnosis.
Lynnwood, Lupus & Sjogren's Moderator, Dx: 2002DIAGNOSING LUPUS & HW's LUPUS 101
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