Vitamin A in cystic fibrosis: case report and review of the literature.

Much has been learned about vitamin A physiology in the last 50 years, yet few changes have been made in therapy. Unfamiliarity with vitamin A bioavailability and distribution may inadvertently result in toxicity. A literature search demonstrates that hypovitaminosis A has rarely been reported in patients with cystic fibrosis, and may manifest very differently in children of different ages. Furthermore, hypervitaminosis A may present with similar features, and can result from correction of deficiency. We report such a case in a 4.5-month-old infant, newly diagnosed with cystic fibrosis, who suffered first from vitamin A deficiency and then vitamin A toxicity. A brief review of vitamin A physiology, deficiency, and toxicity is presented.