Negative = < 20 units Weak positive = 20-39 units Moderate positive = 40-80 units Strong positive = > 80 units

The results will be obtained with the INOVA QUANTA Lite™ ELISA. Assay values obtained with different manufacturers' methods may not be used interchangeably. The magnitude of the reported antibody levels can not be correlated to an endpoint titer. When indirect immunofluorescence test for ANA is positive, the tests for anti-Sm and anti-RNP are helpful in differential diagnoses of various rheumatic diseases. The specificity of the anti-RNP detected is for U-1-RNP (U1-RNP). These two tests are most informative when ordered together in the initial evaluation of patients for autoimmune connective tissue diseases. Anti-Sm is a specific marker antibody for systemic lupus erythematosus (SLE) but is positive in only about one-third of cases. Anti-RNP will also be positive whenever anti-Sm is detected, but can be detected in some SLE patients in the absence of anti-Sm. Anti-RNP may also be found in several other autoimmune connective tissue diseases, however. It is particularly associated with mixed connective tissue disease in which very high levels of anti-RNP are present. The tests are listed together as "anti-RNP/SM" on the current Immunopathology Laboratory requisition (Form A-1a). If this box is checked, then both EIA assays will be performed and two charges will be generated.