How does the ANA profile aid in the diagnosis and management of SLE and related juvenile systemic CTDs?
Although a negative ANA profile does not rule out any of the juvenile systemic CTDs, a positive ANA profile can be extremely useful in making a specific diagnosis. In particular, anti-dsDNA and anti-Smith (anti-Sm) antibodies are specific for SLE; high titers of anti-ribonucleoprotein antibody are suggestive of MCTD; and anti-Ro (SS-A) and/or anti-La (SS-B) antibodies are found in Sjögren syndrome, although this syndrome and antibodies against Ro (SS-A) are most commonly seen as a part of SLE. In addition, anti-histone antibodies may be seen in SLE and in drug-induced lupus. These two diagnoses may be distinguished by the presence of antibodies to specific histones. Finally, a positive ANA is essentially never found in systemic-onset juvenile idiopathic arthritis (Still disease).
Antinuclear Antibody Subtypes in Juvenile Systemic Connective Tissue Disease
|Active SLE||MCTD||SSc||CREST||Primary Sjögren||JIA (Poly)|
|Anti-RNP||30%||>95% titer >1:10,000||Common (low titer)||Neg (low titer)||Rare||Rare|
ANA, antinuclear antibody; anti-RNP, anti-ribonucleoprotein; anti-Sm, anti-Smith antibody; CREST, calcinosis, Raynaud’s phenomenon, esophageal dysmotility, sclerodactyly, telangiectasias; JIA, juvenile idiopathic arthritis; MCTD, mixed connective tissue disease; SLE, systemic lupus erythematosus; SSc, systemic sclerosis/scleroderma.