Zinc toxicity

Background

  • Transition metal
  • Essential nutrient
  • Exposure from diet, medicinal uses, nutritional supplements, and occupational exposures
    • Multiple case reports of zinc toxicity related to ingestion of United States pennies which contain 97.5% zinc

Toxicokinetics

  • Absorbed primarily in the jejunum
  • Excreted via the GI tract with minimal amounts excreted in the urine
  • Accumulates in erythrocytes
    • Whole blood concentrations are 6-7x higher than in the serum
  • Inverse relationship with copper
    • Excess zinc absorption will cause a counterregulatory response resulting in copper elimination

Clinical Features

Acute

Chronic

Differential Diagnosis

Heavy metal toxicity

Evaluation

  • BMP
  • CBC
  • Copper level
  • Ceruloplasmin level
  • Abdominal films to assess for foreign bodies
  • MRI
    • Will show increase T2 signal in the dorsal columns of the cervical cord

Management

  • Oral toxicity
  • Inhalation
  • Chelation
    • Limited data on use, and data present is based off of case reports and treatment for lead toxicity [1]
    • Consider in patients with hemodynamic compromise
    • CaNa2EDTA, British antilewisite, DTPA were all successfully used in case reports
    • 1000mg/m2/d IV CaNa2EDTA every 6 hours
      • Based on a successful case report, but should be given in conjunction with toxicology or poison control center
  • Dermal Exposures
    • Do not use water in metallic zinc exposures
      • Concern metal will ignite
    • Remove zinc with forceps and apply mineral oil to affected skin
  • Copper replacement
    • Oral copper alone shown to improve hematopoietic effects and prevent further neurological deterioration [2]

Disposition

References

  1. Majlesi, N. Zinc. In: Goldfrank's Toxicologic Emergencies. 9th Ed. New York: McGraw-Hill; 2011: 1342
  2. Rowin J, Lewis SL. Copper deficiency myeloneuropathy and pancytopenia secondary to overuse of zinc supplementation. J Neurol Neurosurg Psychiatry. 2005;76:750-751.

Majlesi, N. Zinc. In: Goldfrank's Toxicologic Emergencies. 9th Ed. New York: McGraw-Hill; 2011: 1339-1344