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Hypervitaminosis A
Definition
Hypervitaminosis A is having too much vitamin A in the body.
Alternative Names
Vitamin A toxicity
Causes, incidence, and risk factors
There are two types of vitamin A hypervitaminosis:
- Acute -- caused by taking too much vitamin A over a short period of time
- Chronic -- occurs when too much of the vitamin is present over a longer period
Chronic vitamin A toxicity develops after taking too much vitamin A for long periods.
Symptoms
- Abnormal softening of the skull bone (craniotabes -- infants and children)
- Blurred vision
- Bone pain or swelling
- Bulging fontanelle (infants)
- Changes in consciousness
- Decreased appetite
- Dizziness
- Double vision (young children)
- Drowsiness
- Fatigue
- Headache
- Impotence and ejaculation failure
- Increased intracranial pressure
- Irritability
- Nausea
- Osteoporosis
- Poor weight gain (infants and children)
- Skin and hair changes
- Swelling of breast tissue in men (gynecomastia)
- Vision changes
- Vomiting
Signs and tests
- Bone hardening (calcification)
- High blood calcium levels
- High cholesterol
- High serum creatinine (suggesting kidney damage)
- Serum vitamin A levels
Treatment
Treatment involves simply stopping the use of too much vitamin A.
Expectations (prognosis)
Most people fully recover.
Complications
- Excessively high calcium levels
- Failure to thrive
- Kidney damage due to high calcium
- Liver damage
- Osteoporosis
- Prostate cancer
Recent studies show that taking too much vitamin A during pregnancy can cause abnormal development in the fetus. Talk to your health care provider about eating a proper diet while you are pregnant.
Calling your health care provider
Call your health care provider if you think that you or your child may have taken too much vitamin A, or you have symptoms of excess vitamin A.
Prevention
To avoid hypervitaminosis A, avoid taking more than the recommended daily allowance of this vitamin. Recent emphasis on vitamin A and beta carotene as anticancer vitamins may contribute to chronic hypervitaminosis A, if people take more than is recommended.
References
Zile M. Vitamin A deficiencies and excess. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 45.
Reviewed By: Elizabeth H. Holt, MD, PhD, Assistant Professor of Medicine, Section of Endocrinology and Metabolism, Yale University. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
