What is the next best step for a patient with mild bilateral leg pain, fatigue after walking short distances, and recent decrease in outdoor activities, who has a good diet and appetite, and a normal physical examination?

Diagnostic Approach: Vitamin D Deficiency with Musculoskeletal Manifestations

The correct answer is C: Advise sun exposure and vitamin D supplements. This patient presents with bilateral leg pain, fatigue with minimal exertion, and critically—reduced outdoor activity, which strongly suggests vitamin D deficiency as the underlying cause in the context of a normal physical examination.

Clinical Reasoning

Why Vitamin D Deficiency is Most Likely

• Bilateral leg pain with normal examination in a patient with decreased sun exposure is a classic presentation of vitamin D deficiency-related myopathy 1
• Fatigue after short distances without objective weakness on examination suggests metabolic muscle dysfunction rather than structural pathology 1
• Recent decrease in outdoor activities is the critical historical clue—vitamin D synthesis requires adequate sun exposure, and this patient has eliminated their primary source 1
• Good diet and appetite makes nutritional calcium deficiency less likely as an isolated problem 1

Why Other Options Are Incorrect

Option A (Orthopedic surgery referral) is premature and inappropriate:

• Normal physical examination excludes structural pathology requiring surgical evaluation 2
• No evidence of joint deformity, limited range of motion, or focal tenderness 2
• Bilateral symptoms without trauma suggest systemic rather than orthopedic pathology 1, 3

Option B (Increase outdoor activities alone) is insufficient:

• While increased activity would help, this patient likely has established vitamin D deficiency requiring supplementation 1
• Exercise alone without correcting the underlying deficiency will not adequately address the metabolic muscle dysfunction 2
• The 3-month duration suggests depletion of vitamin D stores that requires active repletion 1

Option D (Calcium + vitamin D) is excessive:

• No evidence of calcium deficiency—patient has good diet and appetite 1
• Adding calcium without documented deficiency or osteoporosis risk is unnecessary 1
• Vitamin D deficiency can occur independently of calcium deficiency 1

Critical Diagnostic Considerations

Rule Out Vascular Claudication

• Pain pattern is atypical for PAD: Does not occur predictably with a specific walking distance and is described as "gradually increasing" rather than exercise-induced 2
• Bilateral presentation without classic claudication makes PAD less likely, though ABI testing could be considered if symptoms persist after vitamin D repletion 3, 4
• Normal physical examination including presumably normal pulses makes significant PAD unlikely 3

Rule Out Spinal Stenosis

• No positional relief pattern: Spinal stenosis improves with sitting/lumbar flexion and worsens with standing/extension 1, 4
• No difficulty rising from sitting, which is characteristic of spinal stenosis 1
• Age and bilateral posterior leg pain could suggest stenosis, but the lack of positional variation and normal examination make this less likely 1

Recommended Management Approach

Immediate intervention:

• Advise 15-30 minutes of sun exposure daily (face, arms, legs) during midday hours when UV-B radiation is optimal 1
• Initiate vitamin D supplementation (typically 1000-2000 IU daily for deficiency prevention, though higher loading doses may be needed if deficiency is confirmed) 1

Follow-up strategy:

• Reassess symptoms in 4-6 weeks after initiating sun exposure and supplementation 1
• If symptoms persist despite adequate vitamin D repletion, obtain resting ABI bilaterally to exclude PAD 3, 4
• Consider serum 25-hydroxyvitamin D level if symptoms do not improve, to confirm deficiency and guide dosing 1

Common Pitfalls to Avoid

• Do not assume vascular disease without characteristic claudication pattern (pain with specific distance, relief within 10 minutes of rest) 2, 4
• Do not overlook environmental/lifestyle factors: Decreased outdoor activity is a modifiable risk factor that directly impacts vitamin D status 1
• Do not order extensive imaging for bilateral symptoms with normal examination—this suggests systemic rather than structural pathology 1, 3
• Do not delay simple interventions: Sun exposure and vitamin D supplementation are low-risk, high-yield interventions that can be initiated empirically 1