Laboratory Workup for Bilateral Upper Extremity Numbness and Tingling
For bilateral upper extremity numbness and tingling, order a focused initial laboratory panel including: complete blood count, comprehensive metabolic profile, fasting blood glucose, vitamin B12, thyroid-stimulating hormone (TSH), and serum protein electrophoresis with immunofixation. 1
Initial Laboratory Testing
The evaluation should focus on identifying treatable systemic causes of peripheral neuropathy, as these account for the majority of identifiable etiologies 1:
- Complete blood count (CBC) – screens for anemia, infection, and hematologic disorders that may cause neuropathy 1
- Comprehensive metabolic profile – evaluates kidney and liver function, electrolyte abnormalities, and metabolic derangements 1
- Fasting blood glucose – diabetes mellitus is the most common identifiable cause of peripheral neuropathy 1
- Vitamin B12 level – deficiency causes bilateral sensory neuropathy and is readily treatable 1
- Thyroid-stimulating hormone (TSH) – hypothyroidism is a recognized risk factor for nerve entrapment and neuropathy 2, 1
- Serum protein electrophoresis with immunofixation – screens for paraproteinemia and monoclonal gammopathies that can cause neuropathy 1
Additional Testing Based on Clinical Context
If the initial workup is unrevealing and symptoms persist, consider:
- Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) – if inflammatory arthritis or vasculitis is suspected based on joint involvement 3
- Rheumatoid factor (RF) and anti-CCP antibodies – if joint swelling is present, as early arthritis can occur with negative ANA 3
- Hemoglobin A1c – if fasting glucose is borderline or prediabetes is suspected 1
Important Clinical Considerations
Bilateral symptoms strongly suggest a systemic etiology rather than focal nerve compression 2. Risk factors that increase likelihood of systemic neuropathy include diabetes, smoking, alcohol consumption, rheumatoid arthritis, and hypothyroidism 2.
Common Pitfalls to Avoid
- Do not order comprehensive autoimmune panels without specific clinical indicators – this leads to false positives and unnecessary patient anxiety 4
- Recognize that 25% to 46% of peripheral neuropathy cases remain idiopathic despite thorough evaluation 1
- Do not delay referral to neurology if initial workup is negative – electrodiagnostic studies (nerve conduction studies and electromyography) may be needed to differentiate axonal from demyelinating disease and guide further testing 1, 5
When to Consider Imaging
While laboratory testing addresses systemic causes, imaging may be warranted if:
- Cervical spine pathology is suspected – MRI cervical spine can identify radiculopathy causing bilateral upper extremity symptoms 5
- Structural nerve compression is suspected – MRI or ultrasound can evaluate peripheral nerve anatomy, though bilateral compression syndromes are uncommon 5
Referral Threshold
If initial laboratory evaluation is inconclusive, refer to neurology for additional testing including electrodiagnostic studies, specific antibody assays, or nerve biopsy 1. Early referral is particularly important if symptoms are progressive, involve weakness or atrophy, or significantly impair function 1.