Systemic Lupus Erythematosus (SLE) Diagnosis
The Systemic Lupus International Collaborating Clinics (SLICC) has come up with criteria to classify someone as having SLE by either having a kidney biopsy that shows lupus (plus be positive for ANA or anti-ds DNA antibodies) OR have 4 or more of the following criteria with at least 1 coming from the "Clinical Criteria" and 1 from the "Immunologic Criteria:"
- Acute cutaneous lupus or subacute cutaneous lupus rash (e.g., the butterfly rash or sun-sensitive rash)
- Chronic cutaneous lupus rash (e.g., discoid lupus)
- Mouth or nose ulcers (usually painless)
- Non-scarring alopecia (hair loss on the scalp that comes back after treatment)
- Non-erosive arthritis, which occurs in 2 or more joints and causes swelling, or tenderness of the joints along with at least 30 minutes of morning stiffness)
- Serositis (e.g., inflammation of the lining around the heart [pericarditis] and/or the lungs [pleurisy])
- Kidney (renal) disorder (e.g., excessive protein in the urine [proteinuria], cellular casts in the urine)
- Neurological disorder (e.g., seizures, psychosis, mononeuritis multiplex, peripheral neuropathy, cranial neuropathy, myelitis, or acute confusional state)
- Hemolytic anemia ( a very specific type of anemia due to the immune system attacking the red blood cells)
- Leukopenia (low white blood cell count)
- Thrombocytopenia (low platelet count)
- Antinuclear antibodies (ANA; positive test in absence of drugs known to induce a positive test)
- Anti-double stranded DNA antibodies
- Anti-Smith antibodies
- Antiphospholipid antibodies (lupus anticoagulant, false positive syphilis test, cardiolipin antibody, or beta-2 glycoprotein I antibody)
- Low complement levels (C3, C4, or CH50)
- Direct Coombs' test (don't count in the presence of hemolytic anemia)
Laboratory Tests to Diagnose Lupus
There is no test that is used specifically to diagnose SLE; however, the disease may affect a number of test results.
Almost all patients with lupus test positive for anti-nuclear antibody (ANA) when it is done using HEp-2 cells; however, as many as 20 percent of healthy women also test positive for this antibody, so the test is not definitive for lupus.
Depending on which organ systems are affected, additional laboratory tests can be used to detect a specific abnormality (e.g., an elevated red blood cell count in the urine if the kidneys are affected) caused by lupus.
In some cases, a biopsy of the kidney or skin can be helpful in making a diagnosis of SLE. Biopsy involves removing a small sample of tissue for microscopic evaluation.