TAILIEUCHUNG - Chapter 071. Vitamin and Trace Mineral Deficiency and Excess (Part 10)

Toxicity Acute toxicity of vitamin A was first noted in Arctic explorers who ate polar bear liver and has also been seen after administration of 150 mg in adults or 100 mg in children. Acute toxicity is manifested by increased intracranial pressure, vertigo, diplopia, bulging fontanels in children, seizures, and exfoliative dermatitis; it may result in death. In children being treated for vitamin A deficiency according to the protocols outlined above, transient bulging of fontanels occurs in 2% of infants, and transient nausea, vomiting, and headache occur in 5% of preschoolers. Chronic vitamin A intoxication is largely a concern in. | Chapter 071. Vitamin and Trace Mineral Deficiency and Excess Part 10 Toxicity Acute toxicity of vitamin A was first noted in Arctic explorers who ate polar bear liver and has also been seen after administration of 150 mg in adults or 100 mg in children. Acute toxicity is manifested by increased intracranial pressure vertigo diplopia bulging fontanels in children seizures and exfoliative dermatitis it may result in death. In children being treated for vitamin A deficiency according to the protocols outlined above transient bulging of fontanels occurs in 2 of infants and transient nausea vomiting and headache occur in 5 of preschoolers. Chronic vitamin A intoxication is largely a concern in industrialized countries and has been seen in normal adults who ingest 15 mg d and children who ingest 6 mg d of vitamin A over a period of several months. Manifestations include dry skin cheilosis glossitis vomiting alopecia bone demineralization and pain hypercalcemia lymph node enlargement hyperlipidemia amenorrhea and features of pseudotumor cerebri with increased intracranial pressure and papilledema. Liver fibrosis with portal hypertension and bone demineralization may result from chronic vitamin A intoxication. When vitamin A is provided in excess to pregnant women congenital malformations have included spontaneous abortions craniofacial abnormalities and valvular heart disease. In pregnancy the daily dose of vitamin A should not exceed 3 mg. Commercially available retinoid derivatives are also toxic including 13-cis-retinoic acid which has been associated with birth defects. As a result contraception should be continued for a least 1 year and possibly longer in women who have taken 13-cis retinoic acid. High doses of carotenoids do not result in toxic symptoms but should be avoided in smokers due to an increased risk of lung cancer. Carotenemia which is characterized by a yellowing of the skin creases of the palms and soles but not the sclerae may be present after .

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