Can a positive ANA occur in a normal healthy individual?
Yes. The frequency depends on ANA titer and patient characteristics:
• ANA 1:40: 20%–30% of healthy individuals can be positive
• ANA 1:80: 10%–15% positive
• ANA 1:160: 5% positive
• ANA 1:320: 3% positive
• Healthy relative of an SLE patient: 5%–25% positive (usually low titers)
• Elderly (age >70 years): up to 70% positive at ANA titer 1:40
