What laboratory test result is often positive in patients with systemic lupus erythematosus (SLE)?

The presence of antinuclear antibodies (ANAs) is a hallmark in the diagnosis of systemic lupus erythematosus (SLE). In SLE, the immune system produces antibodies that mistakenly target and attack healthy cells, leading to systemic inflammation and various autoimmune manifestations. The detection of ANAs is critical because they are typically present in high titers among patients with SLE, with approximately 95% of individuals with the disease testing positive for these antibodies.

While C-reactive protein and erythrocyte sedimentation rate are markers that indicate general inflammation, they are not specific to lupus and can be elevated in a variety of inflammatory conditions. Liver function tests evaluate liver health rather than autoimmune activity, making them less relevant in confirming a diagnosis of SLE. Hence, the antinuclear antibody test is the most significant and often positive laboratory result when considering SLE.