Vitamin A toxicity
Background
- Majority due to chronic ingestion of synthetic vitamin A
- Toxic dose is 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: skin irritation, alopecia arthralgias/bone pain, hyperlipidemia, hepatotoxicity, ataxia, visual impairment, headache, pseudotumor cerebri, elevated ICP
Retinoic 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
- Manage complications of liver failure
- Liver transplant may necessary in severe toxicity w/fulminant liver failure
- Consider tox or poison control consult
Disposition
- Dependant on severity
See Also
External Links
References
- 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.
- Soprano DR, Soprano KJ. Retinoids as teratogens. Annu Rev Nutr 1995; 15:111.
- Mahoney CP, Margolis MT, Knauss TA, Labbe RF. Chronic vitamin A intoxication in infants fed chicken liver. Pediatrics 1980; 65:893.
- 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.
- 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.
- Penniston KL, Tanumihardjo SA. The acute and chronic toxic effects of vitamin A. Am J Clin Nutr 2006; 83:191.
- Smith FR, Goodman DS. Vitamin A transport in human vitamin A toxicity. N Engl J Med 1976; 294:805.
- 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.