What is the best course of treatment for a patient with restless leg syndrome, vitamin D deficiency, hyperlipidemia, and general anxiety disorder who complains of burning pain on the top of their feet?

Burning Foot Pain: Diagnostic Workup and Treatment Algorithm

This patient's burning foot pain most likely represents diabetic peripheral neuropathy or small fiber neuropathy, and requires immediate screening for diabetes, comprehensive neurological examination, and optimization of any underlying metabolic abnormalities before initiating neuropathic pain medications.

Immediate Diagnostic Priorities

Screen for Diabetes First

• Check fasting glucose and HbA1c immediately - diabetic peripheral neuropathy is the most common cause of burning feet in clinical practice, causing symptoms due to small fiber dysfunction 1
• Even if diabetes screening is negative, evaluate for other metabolic causes including thyroid function (TSH, free T4), as subclinical hypothyroidism can cause severe burning feet that resolves completely with hormone replacement 2
• Verify vitamin D levels are being adequately repleted, as the patient has documented vitamin D deficiency which may contribute to both RLS and neuropathic symptoms 3

Comprehensive Foot Examination

• Perform a detailed neurological assessment including:
  • 10-g monofilament testing or Ipswich touch test to assess for loss of protective sensation 4
  • Pinprick, temperature, and vibration testing to evaluate small and large fiber function 4, 1
  • Assessment of lower-extremity pulses, capillary refill time, rubor on dependency, and pallor on elevation 4
• Inspect skin carefully for redness, warmth, dryness, or other changes that might suggest erythromelalgia versus neuropathy 1, 5
• Document presence of foot deformities, calluses, or preulcerative lesions 4

Distinguish Between Key Diagnoses

Diabetic/Metabolic Neuropathy characteristics:

• Burning pain typically worse at night, causing sleep disturbance 1
• Stocking-glove distribution, bilateral and symmetric 1
• Associated with numbness, tingling, and altered temperature perception 1

Erythromelalgia characteristics:

• Episodic burning pain with visible redness and warmth during attacks 1, 5
• Triggered by heat exposure, physical activity, or warm temperatures 1
• Relief with cooling measures and limb elevation 1
• Pain often relieved by dependency (opposite of arterial insufficiency) 5

Treatment Algorithm

Step 1: Address Underlying Causes

Optimize metabolic parameters:

• If diabetes is confirmed, aggressive glucose control is essential to prevent progression of neuropathy 1
• Correct vitamin D deficiency completely - studies show vitamin D supplementation (50,000 units weekly for 2 months) significantly improves RLS severity scores and may benefit neuropathic symptoms 3
• Replace thyroid hormone if hypothyroidism is identified, as this can prompt complete nerve regeneration 2
• Optimize lipid control given documented hyperlipidemia 4

Evaluate and treat RLS appropriately:

• The patient's RLS may be exacerbated by vitamin D deficiency and should improve with repletion 3
• If RLS persists despite vitamin D correction, consider iron studies (ferritin, transferrin saturation) as iron deficiency is strongly associated with RLS 4, 6
• Dopamine agonists like ropinirole are FDA-approved for RLS but should be reserved for persistent symptoms after addressing nutritional deficiencies 7

Step 2: Pharmacologic Management of Neuropathic Pain

First-line medications (if burning pain persists after metabolic optimization):

• Pregabalin, duloxetine, or gabapentin are recommended as first-line agents for neuropathic pain 1
• These medications address the underlying neuropathic pain mechanism rather than just masking symptoms 1

Important caveat: The patient has generalized anxiety disorder - duloxetine may provide dual benefit for both neuropathic pain and anxiety, but monitor for serotonergic effects 1

Step 3: Non-Pharmacologic Interventions

Essential foot care education:

• Inspect feet daily using palpation or visual inspection with a mirror 4
• Use lubricating oils or creams for dry skin 1
• Avoid tight shoes, shoes with rough edges or uneven seams 1
• Never walk barefoot or wear shoes without socks 1
• Avoid chemical agents or plasters for corn/callus removal without professional supervision 1

If erythromelalgia is suspected:

• Avoid heat exposure and excessive exercise triggers 1
• Elevate extremities during symptom flares 1
• Use cooling measures safely - critical warning: avoid excessive cooling strategies like ice water immersion or powerful fans, which increase risk for tissue damage and ulcerations 1
• Consider swimming instead of running for exercise 1

Step 4: Ongoing Surveillance

High-risk foot monitoring:

• This patient requires foot inspection at every visit given symptoms of sensory loss 4
• Annual comprehensive foot evaluation at minimum, but more frequent (every 3-6 months) if loss of protective sensation is confirmed 4
• Refer to podiatry for interprofessional management given burning symptoms and multiple comorbidities 4
• Monitor for development of foot ulcers, as patients with neuropathy and loss of protective sensation are at significantly increased risk 1

Critical Pitfalls to Avoid

• Do not start neuropathic pain medications without first screening for treatable causes - correcting hypothyroidism or vitamin D deficiency may completely resolve symptoms 2, 3
• Do not use footbaths that induce skin maceration 1
• Do not dismiss anxiety symptoms - burning feet syndrome is strongly associated with sleep disturbance, anxiety, and depression that require appropriate management 1
• Do not overlook peripheral arterial disease - assess pulses and consider ankle-brachial index if pulses are diminished or patient has claudication symptoms 4
• Do not delay podiatry referral - interprofessional approach is recommended for patients with sensory symptoms and multiple risk factors 4