(A) Anti nuclear antibody # Antinuclear antibody (ANA) tests are positive in 5 to 10 percent of the general population, a rate that increases with age.> Thus, given a one in 20 frequency for ANAs and a one in 2,000 frequency for systemic lupus erythematosus, only one in 100 persons with a positive ANA test will have the disease.> Consequently, positive ANA test results must be interpreted with caution.> Given the high sensitivity of the currently used substrate for testing, a negative ANA test essentially rules out systemic lupus erythematosus.