* Vitamin A deficiency * Definition: Vitamin A (called retinol in mammals) is a fatsoluble vitamin. The recommended dietary allowance (RDA) for vitamin A is 1.0 mg/day for the adult man and 0.8 mg/day for the adult woman. Since beta-carotene is converted to vitamin A in the body, the body's requirement for vitamin A can be supplied entirely by betacarotene. Sources: The best sources of vitamin A are eggs, milk, butter, liver, and fish, such as herring, sardines, and tuna. Beef is a poor source of vitamin A. Plants do not contain vitamin A, but they do contain beta-carotene and other carotenoids. The best sources of beta-carotene are darkgreen, orange, and yellow vegetables; spinach, carrots, oranges, and sweet potatoes are excellent examples. Cereals are poor sources of beta-carotene. * Vitamin A is called Retinol, Anticancer, Antixerophthalmic. * It is fat soluble, heat stable, destroyed by oxidation or drying. * The target tissue is retina, skin, bone, liver, adrenal. Vitamin A is used in: 1- Used in the eye, it is a component of the eye's light-sensitive parts, containing rods and cones, that allow for night-vision or for seeing in dim-light circumstances. 2-Vitamin A (retinol) occurs in the rods. Another form of Vitamin A, retinoic acid, is used in the body for regulating the development of various tissues, such as the cells of the skin, and the lining of the lungs and intestines. 3-Vitamin A is important during embryological development, since, without vitamin A, the fertilized egg cannot develop into a fetus. 4- Boosts body‘s natural immunity in mouth, respiratory, urinary tract ,thus resistant to infection by vitamin A. Definition of vitamin A deficiency: Vitamin A deficiency exists when the chronic failure to eat sufficient amounts of vitamin A or beta-carotene results in levels of blood-serum vitamin A that are below a defined range. Beta-carotene is a form of pre-vitamin A, which is readily converted to vitamin A in the body. Causes: inadequate intake of foods high in vitamin A (liver, kidney, butter, milk, cream, cheese, and fortified margarine) or carotene, a precursor of vitamin A found in dark green leafy vegetables and yellow or orange fruits and vegetables. (Six mg of beta-carotene is equal to 1 mg of vitamin A.) The recommended daily allowance for vitamin A is 1 mg for adult males and 0.8 mg for adult females. Less common causes include: * Malabsorption due to celiac disease, sprue, cirrhosis, obstructive jaundice, cystic fibrosis, giardiasis, or habitual use of mineral oil as a laxative * Massive urinary excretion caused by cancer, tuberculosis, pneumonia, nephritis, or urinary tract infection * Decreased storage and transport of vitamin A due to hepatic disease. Signs and symptoms : 1-The first symptom of vitamin A deficiency is night blindness (nyctalopia) degeneration of retina , which usually becomes apparent when the patient enters a dark place or is caught in the glare of oncoming headlights while driving at night. 2- xerophthalmia, or drying of the conjunctivas, with development of gray plaques (Bitot’s spots); if unchecked, perforation, scarring, and blindness may result. 3- keratinization of epithelial tissue causes dry, scaly skin; follicular hyperkeratosis; and shrinking and hardening of the mucous membranes, possibly leading to infections of the eyes and the respiratory or genitourinary tract. 4- An infant with severe vitamin A deficiency shows signs of failure to thrive and apathy, along with dry skin and corneal changes, which can lead to ulceration and rapid destruction of the cornea. 5-Retarded growth. Diagnosis: - Dietary history and typical ocular lesions suggest vitamin A deficiency. Carotene levels less than 40 mcg/dl also suggest vitamin A deficiency, but they vary with seasonal ingestion of fruits and vegetables. - Confirming diagnosis A serum level of vitamin A that falls below 10 mcg/dl confirms the diagnosis. Levels between 10 and 19 mcg/dl are also considered low but the patient isn’t likely to have developed significant symptoms. Treatment: -Mild conjunctival changes or night blindness requires vitamin A replacement in the form of cod liver oil or halibut liver oil. -Acute deficiency requires aqueous vitamin A solution I.M., especially when corneal changes have occurred. Therapy for underlying biliary obstruction consists of administration of bile salts; for pancreatic insufficiency, pancreatin. * Dry skin responds well to cream-based or petroleumbased products. * In patients with chronic malabsorption of fat-soluble vitamins, and in those with low dietary intake, prevention of vitamin A deficiency requires aqueous I.V. supplements or an oral water-miscible preparation. *Vitamin A deficiency can be prevented or treated by taking vitamin supplements or by getting injections of the vitamin. * The specific doses given are oral retinyl palmitate (110 mg), retinyl acetate (66 mg), or injected retinyl palmitate (55 mg) administered on each of two successive days, and once a few weeks later if symptoms are not relieved. Supervised by: Dr. Kdriyah EL-Deeb. Prepared by: * Maryam AL-Khawajah. * Faheemah AL-Awami.
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