A 58-year-old diabetic male presents with bilateral symmetric distal numbness, burning pain, and mild weakness of foot dorsiflexion. EMG/NCS shows predominantly axonal sensorimotor neuropathy. What is the stepwise biochemical workup to rule out treatable causes (B12, SPEP, anti-MAG, ANNA-1, vasculitis panel)? When should we pursue nerve biopsy, and what are the red flags for CIDP vs diabetic neuropathy?
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