Lupus is diagnosed using a combination of symptoms and lab tests. Your medical history and that of your family's may also be taken into account. There is no one specific "lupus test." Here are some classic symptoms
extreme fatigue (tiredness)
painful or swollen joints
anemia (low numbers of red blood cells or hemoglobin, or low total blood volume)
swelling (edema) in feet, legs, hands, and/or around eyes
pain in chest on deep breathing (pleurisy)
butterfly-shaped rash across cheeks and nose
sun- or light-sensitivity (photosensitivity)
abnormal blood clotting
unexplained weight loss
fingers turning white and/or blue when cold (Raynaud’s phenomenon)
mouth or nose ulcers
It used to be if you had 4 of the classic symptoms, they would diagnose you with lupus. But these days they seem to be a bit more hesitant to diagnose people with lupus. Don't know why.
Lab tests run when looking for lupus
complete blood count (CBC)
urine test (for kidney involvement)
for autoimmune activity:
Antinuclear antibodies (ANA)
Antibodies to double-stranded DNA (anti-dsDNA)
Antibodies to phospholipids (aPLs)
Antibodies to Ro/SS-A and La/SS-B
Antibodies to Sm
Antibodies to RNP
C-reactive protein (CRP)
Erythrocyte sedimentation rate (ESR or "sed" rate)
Unfortunately, lupus can look very different from one person to another, and also from month to month in the same person. The immune system is attacking the body's healthy tissues, and that could be any tissue. Heart, lungs, kidneys, brain, skin, you name it.
And for this reason it's not uncommon for someone with lupus to go to doctors for 2-5 years before finally getting diagnosed. I was first diagnosed with lung disease (um, no), then bronchitis (what? I wasn't even coughing- there was no phlegm! I've had bronchitis, I know bronchitis, and you sir are no bronchitis!)- the only helpful part about that was they threw antibiotics at me that made me far worse, and therefore easier to diagnose.
The next guess was Rhuematoid arthritis (getting warmer...), and finally, after a night in the ER and a desperate plea to God to just get me a diagnosis, I got a doctor the next day who took enough time with me to get the whole picture, and she diagnosed me. By that time I was so sick, it was easy to diagnose me (once someone listened to me for more than 5 seconds) because I had every single symptom and the horrible lab results. At that point it was so obvious even a caveman could do it...
For this reason, and because our brains and memories are not at their best when we're under attack, I believe it's very important that we keep our own symptom journal when we are actively ill, in order to help the doctors put it all together. It could greatly shorten the amount of time you spend in the waiting room, with no answers and nobody but Judge Judy to keep you company.