What is the next step in managing a patient with a complaint of cold feet, normal laboratory tests, and normal ultrasounds of the bilateral lower extremities?

Management of Cold Feet with Normal Laboratory Tests and Normal Bilateral Lower Extremity Ultrasounds

Obtain a resting ankle-brachial index (ABI) as the next diagnostic step to objectively assess for peripheral artery disease, which is the most common vascular cause of cold feet symptoms. 1

Diagnostic Approach

Why ABI is the Critical Next Step

• The American College of Cardiology recommends obtaining a resting ABI as the initial diagnostic test to confirm or exclude peripheral artery disease (PAD) without requiring any imaging. 1 This is essential because your patient's normal ultrasounds do not rule out PAD—duplex ultrasound is only indicated when revascularization is being considered, not for routine diagnosis. 1

• An ABI ≤0.90 confirms PAD and establishes the diagnosis, while values between 1.00-1.40 are normal. 1, 2 If the resting ABI is normal or borderline (0.91-0.99) but symptoms persist, perform exercise treadmill ABI testing to unmask PAD. 1, 2

• The ABI measurement is performed by obtaining systolic blood pressures at both brachial arteries and both ankle arteries (dorsalis pedis and posterior tibial) using Doppler, then calculating ABI by dividing the higher ankle pressure by the higher arm pressure for each leg. 2

Complete the Vascular Physical Examination

Since laboratory tests and ultrasounds are normal, a thorough vascular examination is essential to identify subtle findings:

• Palpate all pulses bilaterally (brachial, radial, ulnar, femoral, popliteal, dorsalis pedis, and posterior tibial) and record pulse intensity numerically: 0 (absent), 1 (diminished), 2 (normal), or 3 (bounding). 3

• Remove shoes and socks to inspect the feet carefully: evaluate skin color, temperature, integrity of skin and intertriginous areas, and presence of ulcerations. 3

• Look for additional findings suggestive of severe PAD: distal hair loss, trophic skin changes, and hypertrophic nails. 3

• Measure blood pressure in both arms and note any interarm asymmetry, auscultate the abdomen and flank for bruits, and auscultate both femoral arteries for bruits. 3

Refine the Clinical History

The American Heart Association emphasizes documenting specific characteristics of leg symptoms: 3, 2

• Exertional limitation: Ask about fatigue, aching, numbness, or pain in the buttock, thigh, calf, or foot, and the relationship to rest or exertion. 3

• Rest pain: Determine if there is pain at rest localized to the lower leg or foot and its association with upright or recumbent positions. 3

• Wound healing: Inquire about any poorly healing or nonhealing wounds of the legs or feet. 3

• Classic claudication features: Document location, quality, relationship to exertion, time to onset with walking, and time to resolution with rest. 2

If ABI Confirms PAD (≤0.90)

Immediately initiate guideline-directed medical therapy regardless of whether revascularization is planned: 2

• Antiplatelet therapy: Prescribe either aspirin 75-325 mg daily or clopidogrel 75 mg daily to reduce myocardial infarction, stroke, and vascular death. 2

• High-intensity statin therapy: All patients with PAD must receive this regardless of baseline lipid levels. 2

• Supervised exercise program: Prescribe as first-line therapy for claudication—minimum 30-45 minutes per session, at least 3 times weekly for a minimum of 12 weeks. 2

• Antihypertensive therapy: If hypertensive, treat to reduce cardiovascular events. 2

• Consider ACE inhibitor therapy: Recommended for cardiovascular risk reduction in PAD patients. 4

• Screen for abdominal aortic aneurysm: Order duplex ultrasound screening, as the prevalence of AAA is significantly higher in PAD patients. 1, 4, 2

If ABI is Normal (1.00-1.40)

Even with normal ABI, patients can have mild arteriosclerotic disease with atherosclerotic plaques causing less than 50% stenosis: 4

• Implement cardiovascular risk reduction: Smoking cessation, lipid management with statin therapy (LDL <100 mg/dL or <70 mg/dL for very high-risk patients), diabetes management (HbA1c <7%), and hypertension control (BP <140/90 mmHg). 4

• Consider antiplatelet therapy: Aspirin 75-325 mg daily or clopidogrel 75 mg daily as an alternative for those who cannot tolerate aspirin. 4

• Screen for other atherosclerotic disease: Consider screening for abdominal aortic aneurysm with duplex ultrasound, as patients with atherosclerotic disease in one vascular bed have higher prevalence of disease in other arterial beds. 4

• Arrange regular follow-up: Monitor for disease progression and development of symptoms with periodic vascular examination including pulse assessment and inspection of legs and feet. 4

Alternative Diagnoses to Consider

If ABI testing is normal and symptoms persist without vascular explanation:

• Erythromelalgia: A rare condition characterized by redness, warmth, and painful extremities, though it can also present with cyanosis. 5 This diagnosis is made clinically when diagnostic testing is negative.

• Ambient temperature effects: Foot temperature varies significantly with ambient temperature (ranging from 15.9°C in winter to 37.5°C in summer in healthy individuals), and complaints of cold feet may reflect normal physiologic variation. 6

• Neurologic causes: Consider peripheral neuropathy or other neurologic conditions if vascular workup is negative. 7

Common Pitfalls to Avoid

• Do not assume normal ultrasounds exclude PAD: Duplex ultrasound is not a screening test for PAD and is only indicated when revascularization is being considered. 1 The ABI is the appropriate screening test.

• Do not order bilateral imaging for unilateral symptoms without cause: If symptoms were unilateral, bilateral ultrasound screening would have been unnecessary unless predisposing factors were present. 8, 9

• Do not delay guideline-directed medical therapy: If PAD is confirmed, initiate antiplatelet therapy, statin therapy, and exercise therapy immediately—do not wait for imaging or specialist consultation. 1, 2