A 38-year-old woman presents with malar rash, photosensitivity, arthritis, and oral ulcers. Per the 2019 ACR/EULAR classification criteria for SLE, which autoantibody serves as the entry criterion for classification?
- A Anti-Smith (anti-Sm) antibody
- B Anti-double-stranded DNA (anti-dsDNA) antibody
- C Antinuclear antibody (ANA) at a titer of 1:80 or higher ✓
- D Anti-Ro (SSA) antibody
Correct answer: C. Antinuclear antibody (ANA) at a titer of 1:80 or higher
Explanation
The 2019 ACR/EULAR SLE classification criteria require a positive ANA at a titer of 1:80 or higher as the entry criterion before weighted additive clinical and immunological criteria are applied. Anti-dsDNA and anti-Sm are weighted criteria within the classification but do not serve as the entry gate. This structure prevents overdiagnosis in ANA-negative individuals.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.