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Vitamin A status involves eye health via two separate functions. Retinal is an essential factor in rod cells and cone cells in the retina responding to light exposure by sending nerve signals to the brain. An early sign of vitamin A deficiency is night blindness. [6] Vitamin A in the form of retinoic acid is essential to normal epithelial cell ...
Vitamin A deficiency is the leading cause of preventable childhood blindness worldwide and is a major cause of childhood mortality. [1] Each year, approximately 250,000 to 500,000 malnourished children in the developing world go blind from a VAD, with about half of whom dying within a year of losing their sight. [ 2 ]
No vitamin A toxicity has ever been reported from ingestion of excessive amounts. [24] Overconsumption of beta-carotene can only cause carotenosis, a harmless and reversible cosmetic condition in which the skin turns orange. Preformed vitamin A absorption and storage in the liver occur very efficiently until a pathologic condition develops. [21]
Retinol, also called vitamin A 1, is a fat-soluble vitamin in the vitamin A family that is found in food and used as a dietary supplement. [3] Retinol or other forms of vitamin A are needed for vision, cellular development, maintenance of skin and mucous membranes , immune function and reproductive development. [ 3 ]
Bleeding may not be readily apparent; internal organs such as the liver, kidney and spleen may bleed into the abdominal cavity. The only apparent signs may come with blood loss. Bleeding from a bodily orifice, such as the rectum, nose, or ears may signal internal bleeding, but cannot be relied upon.
The causes are vitamin A deficiency during pregnancy, followed by low transfer of vitamin A during lactation and infant/child diets low in vitamin A or beta-carotene. [ 4 ] [ 5 ] The prevalence of pre-school age children who are blind due to vitamin A deficiency is lower than expected from incidence of new cases only because childhood vitamin A ...
Cochlear hydrops preferentially affects the apex of the cochlea where low-frequency sounds are interpreted. Due to the fluid imbalance in this area, parts of the cochlea are stretched or under more tension than usual, which can lead to distortions of sound, changes in pitch perception, or hearing loss, all usually in the low frequencies.
Mayo Clinic is a nonprofit hospital system with campuses in Rochester, Minnesota; Scottsdale and Phoenix, Arizona; and Jacksonville, Florida. [22] [23] Mayo Clinic employs 76,000 people, including more than 7,300 physicians and clinical residents and over 66,000 allied health staff, as of 2022. [5]