Hypocomplementemia is also seen, due to either consumption of C3 and C4 by immune complex-induced inflammation or to congenitally complement deficiency, which may predispose to SLE. Renal disorder: More than 0.5 g per day protein in urine or cellular casts seen in urine under a microscope; sensitivity = 51%; specificity = 94%. Antinuclear antibody test positive; sensitivity = 99%; specificity = 49%. Immunologic disorder: Positive anti-Smith, anti-ds DNA, antiphospholipid antibody, or false positive serological test for syphilis; sensitivity = 85%; specificity = 93%. Presence of anti-ss DNA in 70% of cases (though also positive with rheumatic disease and healthy persons). Neurologic disorder: Seizures or psychosis; sensitivity = 20%; specificity = 98%.Other than the ACR criteria, people with lupus may also have:
Fever (over 100 °F/ 37.7 °C)
Extreme fatigue
Hair loss
Fingers turning white or blue when cold (Raynauds phenomenon)

Criteria for individual diagnosis
Some people, especially those with antiphospholipid syndrome, may have SLE without four of the above criteria, and also SLE may present with features other than those listed in the criteria.Recursive partitioning has been used to identify more parsimonious criteria. This analysis presented two diagnostic classification trees:

Simplest classification tree: SLE is diagnosed if a person has an immunologic disorder (anti-DNA antibody, anti-Smith antibody, false positive syphilis test, or LE cells) or malar rash. It has sensitivity = 92% and specificity = 92%. Full classification tree: Uses 6 criteria. It has sensitivity = 97% and specificity = 95%.Other alternative criteria have been suggested, e.g. the St. Thomas Hospital "alternative" criteria in 1998.
The MAP approach has been further studied in over 40,000 patients tested with either the MAP or traditional ANA testing strategy (tANA), demonstrating patients who test MAP positive are at up to 6-fold increased odds of receiving a new SLE diagnosis and up to 3-fold increased odds of starting a new SLE medication regimen as compared to patients testing positive with the tANA approach.The anti-dsDNA antibody titers also tend to reflect disease activity, although not in all cases. Other ANA that may occur in people with SLE are anti-U1 RNP (which also appears in systemic sclerosis and mixed connective tissue disease), SS-A (or anti-Ro) and SS-B (or anti-La; both of which are more common in Sjögrens syndrome). SS-A and SS-B confer a specific risk for heart conduction block in neonatal lupus.Other tests routinely performed in suspected SLE are complement system levels (low levels suggest consumption by the immune system), electrolytes and kidney function (disturbed if the kidney is involved), liver enzymes, and complete blood count. The lupus erythematosus (LE) cell test was commonly used for diagnosis, but it is no longer used because the LE cells are only found in 50–75% of SLE cases and they are also found in some people with rheumatoid arthritis, scleroderma, and drug sensitivities. Because of this, the LE cell test is now performed only rarely and is mostly of historical significance. Diagnostic criteria
Some physicians make a diagnosis based on the American College of Rheumatology (ACR) classification criteria.