how many tests to confirm or rule out lupus...

is it common to have a positive Ra and ANA test indicating lupus then 3 months later have negative tests? I was then given a diagnosis for fibromyalgia. Should I get further tests?

[jrsytomato]

There is no single test for lupus although a positive ANA usually indicates lupus alone.  Many people test negative on the ANA but still have lupus but the diagnosis may be missed since lupus is an autoimmune disease that can attack any part of the body mimicking many other disorders and diseases.  

From the lupus.org website:

"The ANA can be positive in people with other illnesses, or positive in people with no illness. The ANA can also change from positive to negative, or negative to positive, in the same person. Still, lupus is usually the diagnosis when these antinuclear antibodies are found in your blood."

Was an ana the only test performed other than a CBC?  There are other tests that when abnormal are compared with the symptoms will garner a diagnosis.  Here is a comprehensive list of common abnormalities in patients:

http://cure4lupus.org/store/index.php?main_page=page&id=161&chapter=1

What are your symptoms? Here is something to fill out to bring with you to your appointment.  A doctor won't ask you about every symptom most likely so it helps achieving a diagnosis.  Is there a history of autoimmune diseases in your family? These are all things that you should present to your doctor.  

[karajo]

jrsytomato  is right.  Other illnesses can cause an elevated ANA, especially when it is a low titer.  Elevated ANA can also be seen in rheumatoid arthritis. And since you had an elevated RA, that might be where they need to probe more.

Autoimmune diseases are difficult to dx because the labs can be off one time and normal the next.  Usually when the disease has progressed the labs become more evident.

I encourage you to be patient and do as much research as you possibly can.