Vitamin A (Retinol) Most Popular

The Vitamin A (Retinol) test contains 1 test with 1 biomarker.

Vitamin A is critical for vision, growth, and many cell functions. High concentrations of vitamin A are seen with renal failure, but this is not associated with toxicity, and excessive ingestion. High concentrations are associated with bone fractures. Low concentrations of vitamin A are consistent with fat malabsorption and rarely due to inadequate diet. Vitamin A, vitamin E, and carotene are always extracted and detected simultaneously. This is a free vitamin A (retinol

The following is a list of what is included in the item above. Click the test(s) below to view what biomarkers are measured along with an explanation of what the biomarker is measuring.

Also known as: Retinol, Vitamin A, Vitamin A Retinol

Vitamin A

This test measures the level of retinol in the blood; retinol is the primary form of vitamin A in animals. Vitamin A is an essential nutrient required for healthy vision, skin growth and integrity, bone formation, immune function, and embryonic development. It is required to produce photoreceptors in the eyes and to maintain the lining of the surface of the eyes and other mucous membranes. Deficiencies in vitamin A can impair night vision, cause eye damage, and in severe cases lead to blindness. Acute or chronic excesses of vitamin A can be toxic, cause a range of symptoms, and sometimes lead to birth defects. The body cannot make vitamin A and must rely on dietary sources of vitamin A. Meat sources provide vitamin A (as retinol), while vegetable and fruit sources provide carotene (a substance that can be converted into vitamin A by the liver). Vitamin A is stored in the liver and fat tissues (it is fat-soluble), and healthy adults may have as much as a year's worth stored. The body maintains a relatively stable concentration in the blood through a feedback system that releases vitamin A from storage as needed and increases or decreases the efficiency of dietary vitamin A absorption.