Heavy Metal Testing in Occupational Neuropathy
Test for lead, mercury, arsenic, and cadmium using both blood and urine specimens when evaluating occupational neuropathy. 1
Primary Testing Panel
The essential heavy metals to screen for in occupational neuropathy include:
- Lead - causes predominantly motor neuropathy affecting wrist and finger extensors, or distal sensory-motor neuropathy depending on exposure pattern 2
- Mercury - produces direct peripheral nerve damage with cerebellar symptoms and sensory neuropathy 3, 4
- Arsenic - characterized by symmetric sensory symptoms with numbness and paresthesias in distal extremities 3
- Cadmium - causes axonal, distal, symmetric sensory-motor polyneuropathy that is potentially reversible with cessation of exposure 5
Specimen Collection Strategy
Both blood and urine specimens must be collected, as each provides distinct diagnostic information that cannot be obtained from a single sample type 1. This dual approach is critical because:
- Blood testing detects acute/recent exposure (within 2-12 hours of contact) and correlates best with current body burden and level of impairment 1
- Urine testing provides complementary information about metal excretion and chronic exposure patterns 1
Blood samples should be collected in heparinized tubes 1. Document the timing of specimen collection relative to last known exposure 1.
Additional Considerations
Hair and nail analysis can supplement blood and urine testing but should not replace them 1.
When evaluating atypical or severe neuropathy in diabetic patients, heavy metal testing becomes particularly important as the American Diabetes Association specifically recommends considering heavy metal poisoning in the differential diagnosis 6.
Co-Exposure Context
Workers often face simultaneous exposure to multiple heavy metals, which produces more pronounced impairment of peripheral nerves, particularly affecting small fibers and temperature-dependent pain thresholds 7. This makes comprehensive testing across all four metals essential rather than selective testing.
Clinical Pitfall
The relationship between blood lead levels and neuropathy development is weak, especially for subacute motor neuropathy 2. Therefore, do not rely solely on blood lead levels to exclude lead neuropathy - clinical presentation and occupational history remain paramount even with "normal" levels 2.