Description
Use: Differential diagnosis of hypervitaminosis A. A combination of a low serum carotene level and a low vitamin A suggests inadequate vitamin A nutrition.
Synonyms:
A, Vitamin
Retinol, Serum
Reference Interval: 30-90 µg/dL
Vitamin A is a fat-soluble vitamin that has several important functions in the body:
It helps cells reproduce normally (called "cellular differentiation").
It is essential for good vision -- the first sign of a vitamin A deficiency is often poor sight at night.
It is necessary for the proper development of an embryo and fetus.
Vitamin A also helps keep skin and mucous membranes that line the nose, sinuses, and mouth healthy. It plays a role in proper immune system function, growth, bone formation, reproduction, and wound healing.
Vitamin A comes from two sources: a groups of molecules called retinoids (which are derived from animal sources and includes retinol) and another group called carotenoids (which are derived from plants and includes beta-carotene). The body converts beta-carotene to vitamin A.
Severe vitamin A deficiencies are rare in the developed world: symptoms can include dry eyes, night blindness, diarrhea, and skin problems.
While vitamin A is essential for good health, it can be toxic in high doses. Never exceed the recommended daily allowance without first talking to your doctor.