Antinuclear Antibodies (ANA), Serum

Mayo Clinic Laboratories ELISA ANA screen (ANA2) catalog page comparing ELISA and IFA for common connective tissue diseases and defining quantitative cutoffs for weak vs strong positivity and second-order ENA/dsDNA testing likelihood. Candidate notes: Method is ELISA using HEp-2 lysate supplemented with purified antigens (dsDNA, histone, SS-A, SS-B, Sm, Sm/RNP, Scl-70, Jo-1, centromere B). Reference intervals: Negative <=1.0 U; Weakly positive 1.1-2.9 U; Positive 3.0-5.9 U; Strongly positive >=6.0 U. Mayo states ANA IFA and ELISA were substantially equivalent for common CTDs (SLE, Sjogren, MCTD) in their laboratory cohort. Weakly positive ELISA results are often clinical false positives; second-order ENA/dsDNA detection rose with ANA level, with 88% of second-order positives having ANA >3.0 U. Negative ELISA does not rule out systemic sclerosis, inflammatory myopathies, autoimmune hepatitis, or JIA, for which IFA may be preferable. Limits noted in the record: NY State availability listed as No on this catalog entry; antigen panel is finite compared with IFA. A positive ANA is not a diagnosis. Claims in this record are not verified.

A positive ANA is not a diagnosis. Claims in this record are not verified.

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