Which feature best distinguishes primary Raynaud phenomenon from secondary Raynaud associated with systemic sclerosis?
- A Presence of episodic colour change of white, blue, then red
- B Triggering of attacks by cold exposure or emotional stress
- C Symmetric involvement of both hands beginning before age 30 with normal nailfold capillaries ✓
- D Relief of attacks with calcium channel blockers
Correct answer: C. Symmetric involvement of both hands beginning before age 30 with normal nailfold capillaries
Explanation
Primary Raynaud disease begins in young women, is bilateral and symmetric, has no tissue damage, normal nailfold capillaroscopy, and a negative autoimmune screen. Features suggesting a secondary cause include onset after age 30, asymmetric or single-digit involvement, digital ulcers or pitting scars, abnormal nailfold capillaries, and positive antinuclear antibodies. The triphasic colour change, cold and stress triggers, and response to calcium channel blockers occur in both forms, so they cannot discriminate, which removes the other three options.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.