system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 23 yr. old female came with arthritis, Malar rash, oral ulcers, serositis (pleuritis or pericarditis). The likely investigation to be positive is
assistant
The correct answer is  (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.