Your doctor will begin by reviewing your symptoms, your medical history and your exposure to factors that can trigger lupus flares. Next, he or she will examine you, looking for skin rashes on your face or on sun-exposed skin, tenderness or swelling of the joints and ulcers inside your mouth or nose. Your doctor will listen to your heart and lungs with a stethoscope, checking for signs of inflammation of the membrane covering the heart (pericarditis) or inflammation of the membranes covering the lungs (pleuritis).
If your doctor suspects you have lupus, he or she will order a blood test to look for a type of antibody, called the antinuclear antibody (ANA), that almost all people with lupus have in their blood. However, since the ANA test can sometimes be positive in people who do not have lupus, your doctor may order follow-up blood tests to look for other types of antibodies. Lupus cannot be diagnosed only on the basis of the ANA test.
Your doctor may evaluate your condition using the criteria established by the American College of Rheumatology. Your doctor may diagnose lupus even if you don't meet all of these criteria, which were developed for research studies. If you have had 4 of the 17 lupus criteria at some time during your illness, even if fewer than four are active at the time of diagnosis, the diagnosis is more certain and you may be eligible for entry into a research study of lupus.
At least one of the positive criteria must be "clinical" (causing symptoms or affecting a particular part of the body) and one must be a laboratory abnormality (such as an abnormal blood test). The diagnosis can be established without meeting 4 criteria if a kidney biopsy shows evidence of lupus kidney disease along with certain antibodies (including antinuclear antibodies or anti-ds-DNA) present in the blood).The lupus criteria include the following:
Certain types of rashes (called acute or chronic cutaneous lupus)
Ulcers in the mouth or nose
Pericarditis, confirmed by physical exam or electrocardiogram (EKG), or pleuritis, confirmed by physical findings or chest X-ray
Kidney disorder, confirmed by finding high levels of protein in the urine or other specific urine abnormalities, especially red cells suggesting inflammation in the kidney
Neurological disorder, including seizures or psychosis (a serious psychiatric illness)
Blood disorder, including evidence of red blood cell destruction (hemolytic anemia), low white blood cells (leukopenia) or low platelets (thrombocytopenia)
Immune disorder ó This is established by the finding of certain antibodies in the blood, which may include a positive anti-ds-DNA test, a positive anti-Smith antibody test, a positive test for syphilis even though you don't have syphilis or a positive antiphospholipid antibody test (an antibody associated with miscarriage or blood clots).
A positive ANA test result
Low complement levels (proteins involved in inflammation)
Antibodies linked with red blood cell destruction, called a positive Coombs' test
Other tests that may be done to help diagnose lupus include:
Erythrocyte sedimentation rate (ESR), a blood test that indicates the presence of inflammation
A blood test to check levels of proteins involved in immune function
A skin or kidney biopsy (taking a small tissue sample for laboratory examination)
Additional blood tests for autoantibodies