Vitamin A (Retinol) Test

Vitamin A that is processed in the body from animal sources (derived from fish, liver, eggs, etc.) is known as retinol. Retinol plays an important role in the formation of rhodopsin, a photoreceptor pigment in the retina of the eye. Vitamin A helps to maintain epithelial tissues that line most internal organs, glands and the body's surfaces. Vitamin A is a group of unsaturated nutritional organic compounds, including beta-carotene.

Typically the liver stores 80-90% of the body's vitamin A. Primary Vitamin A deficiency is usually caused by dietary deprivation for a long period of time, but it can also stem from fat malabsorption or liver disorders.

In children with complicated measles, vitamin A can shorten the duration of the disorder and reduce the severity of symptoms and risk of death. The younger the patient, the more severe are the effects of vitamin A deficiency. Mortality rate can exceed 50% in children with severe vitamin A deficiency.

Vitamin A that is derived from plant sources is known as beta-carotene. During digestion, the body converts some beta-carotene to retinol.

Deficient vitamin A levels can lead to:

• Impaired dark adaptation of the eyes/night blindness
• Xerophthalmia, when the eyes fail to produce tears
• Keratinization of the skin and mucous membranes in the respiratory, gastrointestinal tract, and urinary tracts
• Drying, scaling, and follicular thickening of the skin and respiratory infections can result
• In children-- growth retardation and infections

It is easier to get higher amounts of retinol from animal sources than plant sources. Carotenoids are absorbed better from vegetables when they are cooked or homogenized and served with some sort of fat, like oil. Major sources of vitamin A include:

• Liver, beef, chicken, eggs, fish, whole milk, and/or fortified milk
• Leafy, green vegetables
• Yellow vegetables
• Bright or deeply pigmented fruits

Vitamin A deficiency can be more prevalent in people who:

• Have liver disorders
• Have diets that lack fruits and vegetables (individuals who are vegan or vegetarian)
• Are gastrointestinal surgery patients
• Have digestive disorders like celiac disease or Crohn's disease
• Have cystic fibrosis
• Have chronic diarrhea
• Have a bile duct obstruction or giardiasis
• Have cirrhosis

Return to more vitamin deficiency tests here.