Detection and quantitation of DNA is useful in the diagnosis of SLE and is more specific than the antinuclear antibody test. It is positive in about 50 % of cases of SLE. Low titres of anti-dsDNA can be present in normal individuals, and in patients with Sjögren's syndrome, rheumatoid arthritis and other disorders. The presence of anti-dsDNA tends to correlate with lupus nephritis, and the anti-dsDNA level often, but not always, correlates with disease activity in SLE.
RST (rust top)
5-10 mL (1 mL serum)