Vitamin A Toxicity Clinical Presentation
- Author: Mohsen S Eledrisi, MD, FACP, FACE; Chief Editor: George T Griffing, MD more...
History
In acute vitamin A toxicity, a history of some or all of the following may be present:
- Nausea
- Vomiting
- Irritability
- Drowsiness
- Altered mental status
- Abdominal pain
- Blurred vision
- Headache
- Muscle pain with weakness
In chronic vitamin A toxicity, a history of some or all of the following may be present:
- Anorexia
- Hair loss
- Dryness of mucus membranes
- Fissures of the lips
- Pruritus
- Fever
- Headache
- Fatigue
- Irritability
- Weight loss
- Bone fracture[5]
- Bone and joint pains
- Diarrhea
- Menstrual abnormalities
- Epistaxis
Carotenemia, the ingestion of excessive amounts of vitamin A precursors in food, mainly carrots, is manifested by a yellow-orange coloring of the skin, primarily the palms of the hands and the soles of the feet. It differs from jaundice in that the sclerae remain white.
Do not forget to evaluate for ingestion of other potentially toxic substances such as other vitamins, aspirin, and acetaminophen.
Inquire about the intake of other supplements and evaluate for possible overdose accordingly.
Isotretinoin (Accutane), a drug used for the treatment of severe forms of acne, is closely related to the chemical structure of vitamin A. The pharmacology and toxicology of these 2 compounds are similar. Birth defects if taken during pregnancy, intracranial hypertension, depression, and suicidal ideation have been reported with isotretinoin. A careful drug history to uncover this possibility is important in patients presenting with manifestations suggestive of vitamin A intoxication.
Physical
Manifestations of acute toxicity include muscle and bone tenderness, especially over the long bones of the upper and lower extremities, as well as neurologic manifestations with signs of increased intracranial pressure (eg, children may have bulging fontanelles).
Manifestations of chronic toxicity include the following:
- Alopecia
- Skin erythema
- Skin desquamation
- Brittle nails
- Exanthema
- Cheilitis
- Conjunctivitis
- Petechiae
- Premature epiphysial closure in children
- Hepatosplenomegaly
- Peripheral neuritis
- Benign intracranial hypertension
- Ataxia
- Papilledema
- Diplopia
- Hyperostosis
- Edema
- Hepatic hydrothorax[6]
Causes
Carotenemia is the result of excessive intake of vitamin A precursors in foods, mainly carrots. Other than the cosmetic effect, carotenemia has no adverse consequences because the conversion of carotenes to retinol is not sufficient to cause toxicity.
Causes of vitamin A toxicity are generally categorized into acute and chronic. Acute toxicity occurs within a few hours or days after a very large intake as a result of accidental overingestion or inappropriate therapy. The estimated toxic dose is about 25,000 IU/kg. Chronic toxicity appears after ingestion of 25,000 IU or more daily for prolonged periods.
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