Important points about Anti-Smith (anti-Sm) antibodies are:
– This test along with anti-RNP are used to determine the cause of the positive ANA.
– ANA is non-specific and can be seen in Lupus as well as other rheumatic diseases. Anti- Smith antibodies on the other hand are very specific for Lupus.
– Anti -Smith antibodies are seen in 5 to 30 percent if patients with Lupus.
– They are associated with a more severe disease process such as possible kidney involvement especially in blacks.
– Anti-Smith antibodies are not used to monitor Lupus diseases activity.
– They also do not correlate as well with kidney involvement compared to Double stranded DNA.
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