Vitamin A is an important fat-soluble vitamin. Hypervitaminosis A is a condition that is caused by excessive amounts of vitamin A in the body. It can either be acute or chronic.
Vitamin A is a fat-soluble vitamin naturally found in certain foods, such as meat and dairy products. It can also be consumed as a dietary supplement. This vitamin is stored in the liver. Hypervitaminosis A (HA) refers to the excessive consumption of vitamin A which leads to acute or chronic toxicity.
Usually, HA is caused by taking excessive amounts of vitamin A supplements, or the accidental ingestion of its topical forms, such as retinol. Acutely, patients may present with non-specific manifestations that include nausea, vomiting, and anorexia. Children may exhibit features such as failure to thrive, bulging of the fontanelles, visual disturbances, and premature closure of epiphyses. Similarly, visual changes and ocular signs occur in adults, and these may involve blurry vision, photophobia, and conjunctivitis.
Central nervous system (CNS) effects include a decreased level of consciousness, lethargy, ataxia, dizziness, headache, and irritability. Some of the CNS manifestations, namely papilledema and bulging of the fontanelles in infants, are due to raised intracranial pressure precipitated by HA.
HA also promotes an abnormal breakdown of bone tissue, which may lead to hypercalcemia and osteoporosis   . Further systemic consequences of HA are hepatotoxicity, hepatomegaly, splenomegaly, ascites, migratory arthritis, and hepatic hydrothorax  .
Chronic HA affects multiple systems, with features such as arthralgia, bone pain, hair loss, desquamation of skin, eczematous lesions, photosensitivity, and petechiae. Other cutaneous manifestations of HA include angular stomatitis, cheilitis, and brittle nails. Last but not least, hypervitaminosis A has teratogenic effects on the developing fetus.
When HA is suspected, there are several biochemical tests and radiological modalities available to confirm the diagnosis and assess effects of the disease. The biochemical tests include:
Other useful tests include: