Selenium toxicity

Background
  • Essential trace element
  • Deficiency found to be the cause of Keshan disease and Kashin-beck disease
  • Recommended daily dose is 5 μg/d

Uses
  • Gun bluing solution
  • Dietary supplement
  • Antidandruff shampoo
  • Glass decolorizer and manufacturing
  • Insecticide
  • Vulcanization of rubber
  • Used in copper refineries

Toxicokinetics
  • Cofactor in glutathione peroxidase
  • Varied GI absorption
  • Minimal dermal absorption
  • Bioavailability (Lowest - Highest)
    • Elemental selenium
    • Inorganic selenite and selenate salt
    • Selenious acid
  • Limited data on toxicokinetics as it varies amongst compounds

Clinical Features

Acute

Chronic or Selenosis
  • No deaths from chronic exposures
  • Seen in those taking nutritional supplements and in rural areas with farmland that has high selenium levels
  • Alopecia with brittle hair
  • Fatigue
  • Nail deformities
  • Pruritic scalp rash
  • Blistered skin with persistent red color
  • Neurologic

Differential Diagnosis

Heavy metal toxicity

Evaluation
  • BMP
  • LFTs
  • CBC
  • CPK
  • EKG
  • Thyroid function tests
  • Whole blood = 0.1–0.34 mg/L (1.27–4.32 μmol/L)
  • Serum = 0.04–0.6 mg/L (0.51–7.6 μmol/L)
  • Urine < 0.03 mg/L (<0.38 μmol/L)
  • Hair < 0.4 μg/g (0.01 μmol/L)

Management
  • Decontamination
    • Irrigation for dermal exposures
    • Consider activated charcoal or oral gastric lavage in cases that could produce significant toxicity
    • Selenious acid
      • Judicious use of NG lavage (as will cause caustic burns) based on time of ingestion, amount and concentration due to potential for serious systemic poisoning
  • Consult Toxicology or poison control
  • Supportive care
    • Mainstay of treatment
    • Acute toxicities usually require multi system support
  • Pain management
    • 10% sodium thiosulfate solution/ointment to skin, nail, and eyes
      • Relief of pain by reduction of selenium dioxide to elemental selenium
    • Selenium hexafluoride gas exposures
      • Calcium gluconate gel
        • Same treatment as hydrofluoric acid exposures
  • Chelation

Disposition
  • Acute toxicities will likely require ICU level of care
  • Chronic exposures are likely safe for discharge and outpatient follow up

References

    Calellor, D. Selenium. In: Goldfrank's Toxicologic Emergencies. 9th Ed. New York: McGraw-Hill; 2011: 1316-1320

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