Diagnosing lupus can be a tricky business. It cannot be diagnosed on the basis of one symptom or test result. Adding to the difficulty, it is common for lupus symptoms to appear suddenly and then disappear, sometimes for months and years at a time.
While there are a few common symptoms, such as pain and rash, lupus varies widely from one person to the next. This is part of the reason why so many people with lupus see multiple doctors over the course of years before getting an accurate diagnosis.
Diagnostic criteria
The American College of Rheumatology recommends that doctors in the U.S. use one set of criteria to diagnose lupus. “Diagnostic Criteria” is the name for a list of signs, symptoms, and tests that doctors use to decide if someone has a certain disease. The lupus criteria include a specific set of symptoms that your doctor can see, symptoms you report, your medical history, plus test results, to decide whether you have lupus.
The 2019 European League Against Rheumatism/American College of Rheumatology Classification for Systemic Lupus Erythematosus (EULAR/ACR). The EULAR/ACR criteria are:1-4
- Positive antinuclear antibodies (ANA) test with a titer of >1:80 on Hep-2 cells or equivalent positive test
If the ANA test is positive, your doctor will look for additional symptoms that may be a sign of lupus, including:
Mucocutaneous
- Alopecia (hair loss)
- Mouth ulcers
- Rash
Serosal
- Pleural effusion (fluid buildup around the lungs)
- Pericarditis (inflammation of the sac around the heart)
Musculoskeletal
- Inflammation of the joints
Renal
- Proteinuria (high protein levels in the urine)
- Lupus nephritis
Immunologic
- Presence of antiphospholipid antibodies (anticardiolipin, anti-β2GB1 or lupus anticoagulant)
- Low levels of C3 and C4 complements
- Presence of lupus-specific antibodies (anti-dsDNA or anti-Smith)
Symptoms have a point system
Each symptom is worth a certain number of points. Certain symptoms, such as lupus nephritis, are considered more serious and are given more points. To be diagnosed with lupus, you must have a positive ANA test, plus score at least 10 points based on your additional symptoms.
The new EULAR/ACR criteria is thought to be more accurate than the older diagnostic tools you may still hear about:1-4
- 1997 Update of the 1982 American College of Rheumatology Revised Criteria for Classification of Systemic Lupus Erythematosus (ACR)
- 2012 Systemic Lupus International Collaborating Clinics Classification Criteria for Systemic Lupus Erythematosus (SLICC)
It is important to note that the lupus criteria were designed to be used when placing people in research trials. In real life, these criteria do not always apply to everyone.
Some people may technically meet the criteria but not be diagnosed with lupus. This can happen if something else is a better diagnosis or explanation for the findings. On the other hand, people might not fully meet the criteria and still be diagnosed with lupus. This is why it is important to see a rheumatologist to help you interpret your symptoms and lab findings.