Diagnostic Approach for Large-Fiber Peripheral Neuropathy

Diagnostic Rationale

Peripheral neuropathy is a diagnosis of exclusion, and identifying treatable causes is the priority, according to the American Diabetes Association 1
The initial workup should systematically evaluate the most common treatable causes, including vitamin B12 deficiency, hypothyroidism, and monoclonal gammopathy, as recommended by the American Diabetes Association 1

Vitamin B12 level should be checked as nutritional deficiencies are among the most common treatable causes of large-fiber neuropathy, as stated by the American Diabetes Association 1
Thyroid-stimulating hormone should be evaluated as hypothyroidism is a well-established treatable cause, according to the American Diabetes Association 1
Serum protein electrophoresis with immunofixation is essential to screen for monoclonal gammopathy and multiple myeloma, which can cause large-fiber predominant neuropathy, as recommended by the American Diabetes Association 1

Referral to neurology is warranted when clinical features are atypical or diagnosis remains unclear after initial workup, as suggested by the American Diabetes Association and other clinical guidelines 1, 2

Large-fiber predominant neuropathy with proprioceptive ataxia should raise suspicion for vitamin B12 deficiency, hypothyroidism, or paraproteinemic neuropathy, which require specific testing, as stated by the American Diabetes Association 1
Asymmetric presentation or significant autonomic involvement warrants more aggressive workup and earlier neurologist referral, according to clinical guidelines 2

Symptomatic treatment with pregabalin, duloxetine, or gabapentin can be initiated for neuropathic pain if present, as recommended by clinical guidelines 2, 3
Daily foot examination and proper footwear are essential to prevent complications from sensory loss, as suggested by the American Diabetes Association and other clinical guidelines 4, 3