How does the antinuclear antibody pattern and titer aid in the diagnosis and management of SLE

How does the antinuclear antibody pattern and titer aid in the diagnosis and management of SLE?

ANAs are present in the sera of almost all children with active SLE. In fact, the absence of ANAs, particularly at the time of symptomatic disease, essentially eliminates SLE as a diagnostic consideration. The average ANA titer in individuals with SLE is 1:320, although in active disease it may be considerably higher (>1:1280). Changes in the ANA titer are not a useful indicator of disease activity and are not followed subsequent to diagnosis. By contrast, the anti-double-stranded DNA (anti-dsDNA) antibody titer, which is found in >80% of patients, often correlates with disease activity. The “rim” pattern on the ANA, in which fluorescence is seen rimming the nuclear membrane, is pathognomonic of SLE, although rarely seen. The “homogeneous” pattern, in which fluorescence is seen uniformly over the nucleus, is the pattern most commonly seen in SLE, while the “speckled” pattern is the least specific (common in MCTD and Sjögren). The ANA is a highly subjective test, and the pattern and titer vary greatly among laboratories. Low titer false-positives are not uncommon (5%–20% of the healthy population). False-negatives are rare, but if you are convinced of the diagnosis of SLE in a patient, the ANA should be repeated in a different laboratory and/or at a future date.

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