dear Ariel,
autoimmune disorders are so complex and so very hard to crack the case on what really is wrong. it may take years, it may not. it's common for a person who is not a "textbook case" of RA or Lupus to go through many rheumatologists. 
personally i have seen 4, with one being the best in Manhattan and still he was baffled a bit.
the frustrating situation is the "wait & watch" plan wich many of us have to go through. yeah, we're being treated for RA but have a lot of other abnormal blood labs for example...but, in the back of any good physicians' mind will be, "this might turn out to be Lupus in a few years."
it's a scary truth.
but again, like many have said already...the treatments and medications are very similar.
the diseases are similar as well, both being chronic, progressive autoimmune diseases with systemic complications. but sometimes just the fact of "not knowing, or not having a definite name for it" makes a patient feel very vulnerable and a lost of control.
but i'll try to clarify a little bit to see if it helps:
RA: *bilateral (both sides of the body) joint pain, stiffness, tenderness, swelling, heat, redness. multiple joints are usually involved.
*loss of energy, fatigue, low grade fever, weight loss.
*morning stiffness taht lastslonger than an hour.
*Xrays are usefull to detect changes in the joints. early in the disease they may be minimal.
* serum Rheumatoid factor is positive in MOST RA patients...BUT NOT ALWAYS!
*possible anemia
*elevated ESR 0-20 for women under 50 is normal. 0-30 for women over 50 is within normal limits. ESR is an indicator that something of a disease process or inflammation is going on. it can show in RA or Lupus.
so here we see already why docs and ourselves "don't know for sure" sometimes because RA & Lupus share many of the same labs. 
ANA: *this test is a very broad lab to screen for autoantibodies in patients suspected in having ANY systemic rheumatic disease (aka connective tissue diseases) i.e.; RA, Lupus, mixed connective tissue disease, scleroderma, Sjogren's.
* Lupus is difficult to find and Dx because it mimics other AI diseases.
* a positive ANA does not confirm a disease like Lupus. along with clinical symptoms, they need to run specific titers like RNP, Smith, SSA,SCl-70 & Jo-1. these labs should be done to investigate further.
*a positive ANA can be caused by medicines: hydralazine drugs and procainamide.
* in all, all bloodworks should be closely monitored at every Dr. appointment & should be done regularly to check for increases and changes.
there are a few types of Lupus, with SLE being probably the most serious because of multi organ involvement.
Symptoms:
* like all of RA.
* you may notice hair loss and constant infections
* a hallmark sign of SLE is a "butterfly rash" across your nose and cheeks.
*seizures
*abnormal urinalysis
* BUN and creatinine elavated
Ariel, keep at the docs and be mindful of your body & how you feel on a day to day basis. Seek 2 or 3 opinions if needed.
When do you see the doc next?
What's the docs plan of action?
If i can explain anything more please feel free to ask. i've access to a lot of info as i intend to specialize in rheumatics (that is of course when i can get back to work and grad school!)....almost finished but had to leave due to illness....BUT I WILL BE BACK!
this is a battle, and takes courage & strength. we might not feel it sometimes...but i think we who have AI diseases have a lot more strength than we give ourselves credit for.
Sincerely,
erin