Diagnosing Raynaud's Syndrome
Raynaud's syndrome is primarily a clinical diagnosis based on the characteristic triphasic color changes (white, blue, then red) of the digits in response to cold or stress, supplemented by laboratory tests and nailfold capillaroscopy to distinguish primary from secondary disease and identify underlying connective tissue disorders.
Clinical Diagnosis
The diagnosis relies fundamentally on patient history and physical examination findings 1, 2, 3:
- Characteristic color changes: Progressive pallor (white), followed by cyanosis (blue), and finally rubor (red) of the digits in response to cold exposure, vibration, or emotional stress 1, 4
- Episodic nature: Symptoms are typically reversible and occur in discrete attacks 3
- Distribution: Most commonly affects fingers and toes 5
Physical Examination Findings
Key examination elements to document 6:
- Hands: Look for joint deformities (ulnar deviation suggesting rheumatoid arthritis), splinter hemorrhages under nails, and signs of Raynaud phenomenon 6
- Skin changes: Assess for scleroderma, facial changes consistent with rosacea, or seborrhea 6
- Digital ulcers or tissue loss: Indicates secondary Raynaud's with more severe ischemia 2, 4
- Nailfold examination: Essential for capillaroscopy (see below)
Laboratory Testing
When secondary Raynaud's is suspected (older age at onset, severe symptoms, digital ulcers, or features of connective tissue disease), obtain 1, 2:
- Complete blood count 1
- Chemistry screen 1
- Antinuclear antibody (ANA) 1, 5
- Lupus erythematosus test 1
- Rheumatoid factor 1
- Erythrocyte sedimentation rate and C-reactive protein 5
- Thyroid function tests 5
- Protein electrophoresis 5
Nailfold Capillaroscopy
This is the single most important diagnostic test to distinguish primary from secondary Raynaud's and facilitate very early diagnosis of systemic sclerosis 5:
- Abnormal capillaroscopy patterns (dilated capillaries, hemorrhages, capillary loss) suggest secondary Raynaud's and underlying connective tissue disease, particularly systemic sclerosis 5
- Normal capillaroscopy supports primary Raynaud's diagnosis 5
Additional Imaging Studies
When vascular pathology is suspected 5:
- Doppler ultrasound: Recommended to evaluate risk of pathologies in large to medium-sized arteries 5
- Chest X-ray: Part of routine workup when secondary causes are being investigated 5
Distinguishing Primary from Secondary Disease
Primary Raynaud's (benign, idiopathic) characteristics 1, 4, 3:
- Younger age at onset (typically affects younger women) 1, 4
- Bilateral and symmetric involvement 3
- No digital ulcers or tissue necrosis 4
- Normal capillaroscopy 5
- Negative laboratory tests for connective tissue disease 1
Secondary Raynaud's characteristics 2, 4, 3:
- Older age at onset 2
- Associated with systemic diseases (scleroderma, systemic lupus erythematosus, other connective tissue diseases) 1, 2
- Digital ulcers, ischemic lesions, or potential for tissue loss 2, 4
- Abnormal capillaroscopy 5
- Positive laboratory markers for underlying disease 1
Important Caveats
- The episodic nature of Raynaud's means diagnosis often relies on patient self-report, as attacks may not occur during clinical examination 3
- Recent evidence challenges the purely "episodic" paradigm, particularly in systemic sclerosis-related Raynaud's, where symptoms may be more persistent 3
- "Primary Raynaud's" may actually comprise several distinct entities including functional vasospasm, physiological thermoregulatory response, subclinical atherosclerosis, and cold intolerance 3
- Additional tests should be selected based on specific clinical suspicion from history and physical examination 1