Diagnosing Raynaud's Phenomenon
Raynaud's phenomenon is primarily a clinical diagnosis based on the characteristic triphasic color change of the digits (white → blue → red) triggered by cold exposure or emotional stress, supplemented by laboratory testing and nailfold capillaroscopy to distinguish primary from secondary forms. 1, 2, 3
Clinical Diagnosis
The diagnosis relies on patient history describing the classic presentation:
- Triphasic color change: Digits turn white (pallor from vasoconstriction), then blue (cyanosis), then red (reactive hyperemia) 2, 4
- Triggering factors: Episodes provoked by cold exposure, humidity, vibration, or emotional stress 2, 4
- Episodic nature: Attacks are reversible and paroxysmal, typically affecting fingers or toes 4
The clinical history alone establishes the diagnosis—no specific "test" is required to confirm Raynaud's phenomenon exists 3, 4
Distinguishing Primary from Secondary Raynaud's
Once Raynaud's is diagnosed clinically, the critical next step is determining whether it is primary (benign, idiopathic) or secondary to underlying disease:
Features Suggesting Primary Raynaud's:
- Symmetric involvement of individual digits 5
- Absence of digital ulcers, tissue necrosis, or gangrene 5
- No systemic symptoms (joint pain, skin changes, weight loss, fever) 5, 6
- Normal peripheral pulses 5
- Typical discomfort only, not severe pain 1, 5
Red Flags for Secondary Raynaud's:
- Asymmetric attacks or involvement of entire hand rather than individual digits 5, 6
- Severe, painful episodes beyond typical discomfort 1, 5
- Digital ulcers, tissue necrosis, or gangrene 1, 5, 6
- Systemic symptoms: Joint pain, skin thickening, telangiectasias, weight loss, malaise, fatigue, fever, photosensitivity, dry eyes/mouth 5, 6
- Abnormal or absent peripheral pulses suggesting atherosclerosis or thromboangiitis obliterans 5
Laboratory and Diagnostic Workup
For All Patients with Raynaud's:
- Complete blood count with differential 1, 5, 7
- Erythrocyte sedimentation rate (ESR) 1, 2, 4
- Antinuclear antibodies (ANA) 1, 7, 2, 4
- Nailfold capillaroscopy: Essential for early detection of underlying connective tissue disease; normal capillaries support primary Raynaud's 2, 4
Additional Testing When Secondary Raynaud's is Suspected:
- Rheumatoid factor 1, 5, 7
- Anticentromere antibodies and anti-Scl-70 antibodies (for systemic sclerosis) 1, 5
- Anticardiolipin antibodies and lupus anticoagulant (for antiphospholipid syndrome) 1, 5
- Ankle-brachial index (ABI): To exclude structural macro- or microvascular disease if peripheral arterial disease is suspected 1, 5
- Digital photoplethysmography and pulse contour analysis: Can exclude structural vascular disease 4
Diagnostic Criteria for Primary Raynaud's:
Primary Raynaud's is diagnosed when ALL of the following are present 4:
- Typical clinical symptoms
- Normal ESR
- Negative ANA
- Normal nailfold capillaries
- Absence of structural micro- or macrovascular damage
- No evidence of underlying disease
Important Caveats
- Upper extremity arterial testing (including ABI-equivalent studies) was rated as uncertain for Raynaud's phenomenon by ACC/AHA guidelines, suggesting it should not be routine unless there are specific concerns for structural vascular disease 8
- The presence of Raynaud's phenomenon in the context of critical limb ischemia is a risk factor for limb loss, particularly when combined with diabetes, severe renal failure, or smoking 8
- Systemic sclerosis is the most common underlying disease in secondary Raynaud's, with 22.5% of these patients developing digital ulcers 1, 5, 6
- Patients with suspected thromboangiitis obliterans (Buerger's disease) should be specifically asked about tobacco use, as this is particularly associated with secondary Raynaud's in young smokers 1, 6