Knowra Vitamin A deficiency Vitamin A deficiency Vitamin A deficiency is a shortage of vitamin A that disrupts vision, immune defenses, growth, and the maintenance of epithelial tissues. Severe deficiency can cause night blindness and irreversible corneal damage.
Night blindness : Difficulty seeing in dim light, often caused by impaired retinal function. It is a common early visual symptom as vitamin A stores decline.
Retinal : A vitamin A-derived aldehyde that binds opsin proteins to form light-sensitive visual pigments. Reduced retinal availability impairs rhodopsin regeneration and dim-light vision.
Vitamin A : A group of fat-soluble compounds required for vision, gene regulation, growth, and immune function. The deficiency results when the body lacks enough of this essential nutrient.
Serum retinol : The concentration of retinol in blood serum, used as an indicator of vitamin A status. It helps assess deficiency, especially in populations, though infection can distort results.
Vitamin A toxicity : Harmful effects caused by excessive vitamin A intake or accumulation. Excess preformed vitamin A can also damage health, making treatment dose important.
Xerophthalmia : A spectrum of eye disease caused by vitamin A deficiency, from conjunctival dryness to corneal destruction. It names the progressive eye damage that can follow untreated deficiency.
Rhodopsin : A light-sensitive pigment in rod cells, formed from the protein opsin and 11-cis-retinal. Vitamin A shortage limits the retinal needed to rebuild this pigment after light exposure.
Retinol : A vitamin A alcohol found in animal foods and used to transport and store vitamin A. Dietary retinol supplies preformed vitamin A that can be depleted in deficiency.
Retinol-binding protein : A blood protein that transports retinol from the liver to tissues. Its concentration is used as a proxy for vitamin A status in some surveys.
Vitamin D deficiency : A shortage of vitamin D that can impair calcium balance and bone mineralization. It is another fat-soluble vitamin deficiency, but its hallmark effects differ from ocular disease.
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