The antinuclear antibody (ANA)test is positive in almost all people who have systemic lupus erythematosus (SLE).It is also positive in some patients who do not have SLE.The antideoxyribonucleic acid (anti-DNA)test is positive only in people with SLE but not in all who do.Which of the following is true?

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Quizplus · Accepted Answer

Because almost all patients with SLE have a positive ANA test,it is a good screening test (if the result is negative,it practically rules out this diagnosis for a patient).However,because the ANA test is also positive in other patients,the anti-DNA test is a good confirmatory test,because only patients with SLE have a positive result.In practice,the ANA test is done first;if it is positive,then the anti-DNA test is done as follow-up.If a patient is positive with both tests,then his or her diagnosis is SLE.

The Antinuclear Antibody (ANA)test Is Positive in Almost All People