Renal involvement may be benign and asymptomatic or relentlessly progressive and fatal. The most common manifestation is proteinuria. The histopathology of the renal lesion varies from a focal, usually benign glomerulitis to a diffuse membranoproliferative glomerulonephritis. Because milder cases of lupus have been increasingly detected, the percentage of patients with clinically significant renal disease has declined. There is no evidence of underlying infection.
Patients respond promptly to corticosteroids.
Anti-Ro is the causal antibody for neonatal lupus and congenital heart block. They may be associated with a positive test for the lupus anticoagulant or a prolonged partial thromboplastin time. Anticardiolipin antibodies may be directly assessed by enzyme-linked immunosorbent assay. Serum complement levels are often depressed in active disease and are usually lowest in patients with active nephritis. ESR is elevated almost uniformly during active disease.