1:40 versus 1:640 Going Beyond the Basics or Ordering, Interpreting ANA Panels
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Clinical Practice
• A 1:40 ANA test is found in 32% in healthy individuals; but the higher the titer, the higher the suspicion of systemic disease.
• Positive ANA tests can be caused by thyroid disease, liver disease, infections, malignancy, pregnancy, and many drugs (esp. TNF inhibitors).
• With chronic cutaneous lupus, need to check renal function, DS-ANA, and complement levels every 6 months.
• Drug -induced lupus usually occurs 6 weeks to several years after initiation of a drug; most often RoANA+; terbinafine most common culprit.