Vitamin A toxicity

Background

  • Majority due to chronic ingestion of synthetic vitamin A
    • Approximately 10x higher than Recommended Dietary Allowance (RDA), totaling ~50,000 units
  • Provitamin A (beta-carotene) ingestion very unlikely to cause toxicity
    • Carotenemia common in children eating leafy green vegetables or carrots, with spontaneous resolution after cessation of foods


Clinical Features

Acute toxicity

  • Single dose >660,000 IU (>200,000 micrograms)
  • Symptoms include nausea, vomiting, vertigo, blurry vision

Chronic toxicity

  • Greater than x10 amount of RDA
  • Symptoms include ataxia, alopecia, hyperlipidemia, hepatotoxicity, bone and muscle pain, visual impairment

Retanoic acid in 1st trimester

  • Very teratogenic
    • Spontaneous abortions and fetal malformation
    • Vitamin A in pregnancy safe upper limit 10,000IU

Differential Diagnosis

Evaluation

  • Vitamin A stored in liver-circulating vitamin A will likely not reflect vitamin A stores
  • Measurement of serum retinyl esters more accurate in fasting state

Management

  • Discontinue high vitamin A intake
    • Most fully recover
  • Vitamin E supplementation
  • Liver transplant if necessary

Disposition

See Also

External Links

References

  1. McCuaig LW, Motzok I (July 1970). "Excessive dietary vitamin E: its alleviation of hypervitaminosis A and lack of toxicity". Poultry Science. 49 (4): 1050–1. doi:10.3382/ps.0491050. PMID 5485475.
  2. Soprano DR, Soprano KJ. Retinoids as teratogens. Annu Rev Nutr 1995; 15:111.
  3. Mahoney CP, Margolis MT, Knauss TA, Labbe RF. Chronic vitamin A intoxication in infants fed chicken liver. Pediatrics 1980; 65:893.
  4. Lam HS, Chow CM, Poon WT, et al. Risk of vitamin A toxicity from candy-like chewable vitamin supplements for children. Pediatrics 2006; 118:820.
  5. Cheruvattath R, Orrego M, Gautam M, et al. Vitamin A toxicity: when one a day doesn't keep the doctor away. Liver Transpl 2006; 12:1888.
  6. Penniston KL, Tanumihardjo SA. The acute and chronic toxic effects of vitamin A. Am J Clin Nutr 2006; 83:191.
  7. Smith FR, Goodman DS. Vitamin A transport in human vitamin A toxicity. N Engl J Med 1976; 294:805.
  8. Krasinski SD, Russell RM, Otradovec CL, et al. Relationship of vitamin A and vitamin E intake to fasting plasma retinol, retinol-binding protein, retinyl esters, carotene, alpha-tocopherol, and cholesterol among elderly people and young adults: increased plasma retinyl esters among vitamin A-supplement users. Am J Clin Nutr 1989; 49:112.

Authors:

Ross Donaldson