Arsenic toxicity

Background

  • Heavy metal
  • Readily absorbed via GI tract and inhalation, poorly via skin
  • Tasteless and odorless
  • Organic trioxide form used as chemotherapeutic agent
  • Trivalent form, As3+, is toxic to over 200 intracellular enzymes
  • Known carcinogen: skin, lung, other
  • Ingestion fatal dose: 100-200mg

Sources of Exposure

  • Poisoning
  • Contaminated drinking water
  • Eruptions
  • Metal and semiconductor industry
  • Wood preservatives
  • seafood arsenic (felt to be organic form which is NONTOXIC and cleared from body in few days)

Clinical Features

Acute ingestion

Arsine gas exposure

Subacute or chronic poisoning

  • Anemia
  • Peripheral neuropathy
    • Typically symmetric "glove and stocking" distribution
  • Skin changes
  • White lines on the finger nails known as "Mees lines"
  • Ataxia
  • CNS Depression
  • Risk factor for squamous cell carcinoma

Differential Diagnosis

Heavy metal toxicity

Acute diarrhea

Infectious

Noninfectious

Watery Diarrhea

  • Enterotoxigenic E. coli (most common cause of watery diarrhea)[1]
  • Norovirus (often has prominent vomiting)
  • Campylobacter
  • Non-typhoidal Salmonella
  • Enteroaggregative E. coli (EAEC)
  • Enterotoxigenic Bacteroides fragilis

Traveler's Diarrhea

Evaluation

Workup

  • Urine arsenic level
  • ECG to eval for QT Prolongation in acute exposure
  • CBC and retic count, expect hemolytic anemia
  • BMP, Mg, Phos, Ca, LFTs, CK
  • Type and screen for possible transfusion in arsine gas exposure
  • CXR if respiratory symptoms 
  • Consider other ingestion labs including acetaminophen and salicylate level in intentional ingestions

Diagnosis

  • Urine arsenic level (usual normal level is <50mcg/L); both urine spot test and 24h urine collection
    • Lab must differentiate inorganic from organic arsenic (treat for inorganic exposure only)
  • Blood arsenic level not helpful (cleared within 2 hrs of exposure)

Management

  • Supportive care, ABCs, IV, O2, monitor
  • Removal from exposure
  • NO Charcoal if co-ingestion is not suspected - adsorbs poorly to arsenic
  • Consider Whole Bowel Irrigation if large radiopaque material in GI tract on xray
  • Airway management and mechanical ventilation if acute inhalation of arsine gas and respiratory distress
  • IV fluids
  • CHELATION therapy: if severe symptoms present
  • Dimercaprol (BAL). 3-5mg/kg IM Q4-6h

Disposition

  • Admit patient's with significant symptoms
  • ED observation and discharge with follow-up for mildly symptomatic

See Also

References

  1. Marx et al. “Cholera and Gastroenteritis caused by Noncholera Vibrio Species”. Rosen’s Emergency Medicine 8th edition vol 1 pg 1245-1246.
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