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Hypervitaminosis A

Last updated May 4, 2018

Approved by: Krish Tangella MD, MBA, FCAP

Vitamin A (also known as retinol) is a key nutrient required for the formation and preservation of healthy bones, skin, teeth, and soft tissues. It is also responsible for producing certain pigments found in the eye, and aids in reproduction and breastfeeding.

What are the other Names for this Condition? (Also known as/Synonyms)

  • Vitamin A Excess Intake
  • Vitamin A Toxicity

What is Hypervitaminosis A? (Definition/Background Information)

  • Vitamin A (also known as retinol) is a key nutrient required for the formation and preservation of healthy bones, skin, teeth, and soft tissues. It is also responsible for producing certain pigments found in the eye, and aids in reproduction and breastfeeding
  • If abnormally excess amounts of vitamin A builds-up in the liver, due to sudden overdose of the substance, or through accumulation of small doses over prolonged periods of time, it leads to a toxic condition called Hypervitaminosis A
  • Most common cause of Hypervitaminosis A is through excess supplementation or accidental overdose of vitamin A
  • This disorder causes blurred vision, softened skull bones in children, dizziness, vomiting, liver damage, hair and skin problems
  • Discontinuation of vitamin A intake, together with symptomatic treatment, are the management measures generally adopted

Who gets Hypervitaminosis A? (Age and Sex Distribution)

  • Children (including infants) and adults, who are administered high doses of vitamin A, may be affected with Hypervitaminosis A
  • Both male and female sex population are uniformly affected. However, it is reported that adult females more commonly take vitamin A supplements, and are hence higher prone to the condition
  • Current research does not indicate any particular racial/ethnic predominance. But, those in the higher educational and economic strata, seem to use more vitamin supplementation and hence, the incidence of Hypervitaminosis A is higher in this group

What are the Risk Factors for Hypervitaminosis A? (Predisposing Factors)

Risk factors of Hypervitaminosis A include:

  • Accidental administration of large doses of vitamin A, especially to infants and children, could lead to acute conditions of Hypervitaminosis A
  • Individuals, who regularly enhance their dietary intake of vitamin A, using vitamin A supplement drugs, are at a high risk for chronic forms of this disorder

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Hypervitaminosis A? (Etiology)

The body requires a specific amount of vitamin A each day. The liver stores vitamin A, which gets transported to various parts of the body by a specific protein, termed as retinol-binding protein.

There is a definite limit to the storage ability of liver, and vitamin A ‘carrying and dissemination’ capacity of the protein. Thus, there exists a fine balance inthe body requirement of vitamin A and the quantity of liver-protein, which is responsible for vitamin A transport in the body.

  • Any intake (dietary or medication) of abnormally high levels of vitamin A, causes excessive storage in the liver, upsets the normal balance, and leads to Vitamin A Toxicity
  • Furthermore, vitamin A is a type of fat-soluble vitamin; it does not quite easily get excreted out of the body, through urine (unlike other water-soluble vitamins, such as vitamins B and C)
  • Based on the quantity levels and time period of accumulation, there are two kinds of Hypervitaminosis A. These are termed Acute Hypervitaminosis A and Chronic Hypervitaminosis A
    • Acute Hypervitaminosis A is the sudden ingestion of large amounts of vitamin A
    • Chronic Hypervitaminosis A is the regular intake of smaller amounts of vitamin A, for a longer duration

The types of fat-soluble vitamins include vitamins A, D, E, and K, which in excess amounts can lead to toxic effects in the body.

What are the Signs and Symptoms of Hypervitaminosis A?

Signs and symptoms are subdivided as acute Hypervitaminosis A and chronic Hypervitaminosis A. These include the following:

Acute Hypervitaminosis A:

  • Vomiting and nausea
  • Loss of appetite, weakness, drowsiness, irritability
  • Blurred vision, headache
  • Mental problems
  • Pain, tenderness in muscle and bone (usually the limbs)
  • Infants, children may have softened skull; increased intracranial pressure in the brain may be observed

Chronic Hypervitaminosis A:

  • Loss of appetite, weakness, drowsiness, irritability
  • Anemia, weight loss
  • Bone and joint problems, which include pain, fracture
  • Hair loss, skin abnormalities (fissures on the lips, itchy sensation)
  • Headache, lack of sleep
  • Diarrhea
  • Nosebleeds
  • Menstrual problems

How is Hypervitaminosis A Diagnosed?

Apart from a physical exam and evaluation of medical history, the diagnostic tests performed for Hypervitaminosis A could include:

  • Blood serum analysis, total blood count
  • Liver function tests
  • Testing of the bones: X-rays, bone mineral density evaluation
  • CAT scan of head and neck region, MRI of brain
  • Electrocardiogram (ECG), to test the effect of high calcium levels on the functioning of the heart

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Hypervitaminosis A?

Complications due to Hypervitaminosis A are:

  • Hypercalcemia (buildup of large amounts of calcium):
    • It can cause kidney damage, such as formation of kidney stones
    • And electrical problems in the heart, resulting in heart dysfunction
  • Liver toxicity, liver damage, which may lead to jaundice (yellowing of the skin)
  • Delayed growth in infants and children resulting in short stature (decreased height)

How is Hypervitaminosis A Treated?

Management of Hypervitaminosis A is usually by achieved by immediately stopping the intake of excess vitamin A, and treating symptoms accordingly:

  • Stoppage of excess vitamin A, till body attains the required level of vitamin A storage
  • Hospitalization is required if the individual is affected neurologically, suffers severe dehydration, or shows high levels of calcium. This is especially important in acute Hypervitaminosis A condition
  • Close observation and treatment with fluid supplementation or water pills, depending on the hydration status of the body. In case of dehydration of the body, fluids are administered, and if excess body water retention is observed, then water pills are used
  • Lumbar puncture and medications are used to relieve the increased intracranial pressure. An increased intracranial pressure can severely affect function of the brain

How can Hypervitaminosis A be Prevented?

  • Vitamin A Toxicity is a disorder that can be completely avoided or prevented, if the required Vitamin A daily allowance is known and administered accordingly
  • By educating individuals (usually adults), who self-medicate or regularly consume vitamin supplements, on the recommended daily dose of these nutrients

What is the Prognosis of Hypervitaminosis A? (Outcomes/Resolutions)

  • Discontinuing the intake of excess vitamin A, and treating the symptoms are sufficient enough to ensure a full recovery. The prognosis is excellent, if the condition is recognized early and treated appropriately
  • Individuals with severe conditions of Hypervitaminosis A may require hospitalization with extended treatment. Some amount of liver, kidney, nervous system damage may be observed, if the treatment is delayed. However, mortality from Vitamin A Excess Intake, is highly infrequent

Additional and Relevant Useful Information for Hypervitaminosis A:

Abnormally large amounts of vitamin A in pregnant women can cause fetal birth defects, or malformations.

What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

Helpful Peer-Reviewed Medical Articles:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Dec. 15, 2013
Last updated: May 4, 2018