Antibody Screen Test – Negative, Positive

The result of antinuclear antibody (ANA) tests is an optical density value (a photometric scale) that is read as positive, negative, or equivocal.

The reference range for antinuclear antibody is negative by ELISA.

A negative value indicates that the diagnosis of a connective tissue disease is unlikely. Any value greater than or equal to 1:160 is significantly positive (in some laboratories, this is reported in international units in which 1 IU is equivalent to 1:160).

The degree of clinical positivity is as follows:

  • Less than or equal to I.0 U is negative.
  • 1.1-2.9 U is weakly positive.
  • 3.0-5.9 U is positive.
  • Greater than or equal to 6.0 U is strongly positive.

Keywords: IAT; Indirect Anti-human Globulin Test; Indirect Antiglobulin Test; Indirect Coombs Test; Red Blood Cell (RBC) Antibody Screen; Red Blood Cell Antibody Screen

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