Medical Archive

Arsenic

Exposure to pesticides/insectisides, contaminated water, pressure-treated wood, metallurgy, mining or glass-making.

Metabolism

• Bind to sulfhydryl groups ? disrupts cellular respiration
  • Inhibition of pyruvate dehydrogenase
  • Gluconeogenesis and glutathione metabolism

Toxicity

• Acute
  • Abdominal pain, vomiting, severe watery diarrhea ? dehydration
  • Garlic odor on the patient’s breath or stool
  • QTc prolongation ? TdP
• Chronic
  • Stocking-glove neuropathy
  • Skin
    • Early: Hypo/hyperpigmentation
    • Late: Hyperkeratosis and scaling on the palms and soles
    • Mees lines (horizontal striation of fingernails)

Diagnosis

Treatment

• Dimercaprol
  • ?Urinary excretion by forming soluble chelates
  • Narrow TDI: nephrotoxicity
• DMSA

Cadmium

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Lead

• Occupational exposure
  • Lead paint, batteries, ammunition, construction

Metabolism

• Absorption
  • In adults, predominantly via the lungs
• Distribution
  • Throughout the blood, bones, and other organs
  • Predominantly stored in the skeleton and is released slowly, potentially exerting its pathologic effects over decades

Toxicity

• Neurologic
  • Irritability, headache
  • Short-term memory loss
  • Motor – weakness
  • Sensory – loss & numbness in a stocking-glove distribution bilaterally.
  • Ataxia
• Gastrointestinal
  • Constipation, abdominal pain, anorexia
• Renal
  • Interstitial nephritis
• Laboratory findings
  • Anemia
  • Hyperuricemia

Diagnosis

1. Screening
   • Routinely performed at 12 and 24 months for patients living in high-risk areas (pre-1950s homes or zip cods with high percentages of elevated blood lead levels).
   • Universal screening is not recommended.
2. Fingerstick test
   • False-positive results are common d/t environmental contamination and improper collection.
   • Confirmatory venous lead measures if a screening capillary lead level is ?5µg/dL.
3. Serology, if elevated.
   • Serum lead level
   • Hyperuricemia
   • CBC: microcytic, hypochromic anemia
   • PBS: basophilic stippling

Treatment

According to blood lead level

• <5 µg/dL
  • Family education and annual test of blood lead levels.
• 5-14 µg/dL
  • Retest at 1-3 months, remove sources of lead exposure.
• 15-44 µg/dL
  • Retest at 1-4 weeks, remove sources of lead exposure.
• 45-69 µg/dL
  • Retest within 48 hours along with further workup (x-ray of the abdomen, electrolytes, etc)
  • Begin chelation therapy – oral succimer is recommended
• > 70 µg/dL
  • Retest within 24 hours, urgent evaluations, hospitalization, and chelation therapy – succimer + CaNa2EDTA

Chelating therapy

• ?Urinary excretion by forming non-ionizing salts
• Deferoxamine
• CaNa2EDTA
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  • BAL? ?? ? ? 1,000mg/m2/day?? ??? ?? ? ??.

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• Penicillamine
  • ?, ??, ?? ??? ??? monitoring.
• DMSA (2,3-dimer-captosuccinic acid)
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# Environmental measures

• Wallpapering over walls painted with lead-based paint
  • Pain can still loosen underneath the paper and release lead dust.
• Lead paint should be encapsulated or removed by a professional to avoid exposure.

Mercury

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