{"id":4422619,"date":"2025-01-12T08:07:18","date_gmt":"2025-01-12T14:07:18","guid":{"rendered":"https:\/\/myendoconsult.com\/learn\/topics\/vitamin-a-deficiency\/"},"modified":"2025-01-12T08:10:18","modified_gmt":"2025-01-12T14:10:18","slug":"vitamin-a-deficiency","status":"publish","type":"oen_topic","link":"https:\/\/myendoconsult.com\/learn\/topics\/vitamin-a-deficiency\/","title":{"rendered":"Vitamin A Deficiency"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">OVERVIEW oF VITAMIN A DEFICIENCY<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Vitamin A<\/strong>: A family of lipid-soluble compounds (retinols, \u03b2-carotenes [provitamin A], and carotenoids) known as retinoic acids.<\/li>\n\n\n\n<li><strong>Key roles<\/strong>: Phototransduction (particularly night vision), epithelial tissue growth\/differentiation, bone growth, and immune function.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">DIETARY SOURCES &amp; ABSORPTION<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Food sources<\/strong>:\n<ul class=\"wp-block-list\">\n<li>Retinol-rich foods: <strong>Liver, egg yolk, kidneys, fish oils, and butter<\/strong>.<\/li>\n\n\n\n<li>\u03b2-Carotene sources: <strong>Green leafy vegetables (e.g., spinach), carrots, sweet potatoes, apricots, tomatoes, pimentos<\/strong>.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>\u03b2-Carotene \u2192 Vitamin A<\/strong>: In the GI tract, 1 molecule \u03b2-carotene can yield 2 molecules of vitamin A.<\/li>\n\n\n\n<li><strong>Absorption<\/strong>:\n<ul class=\"wp-block-list\">\n<li>Occurs in <strong>jejunum and ileum<\/strong>.<\/li>\n\n\n\n<li>After absorption, enterocytes form retinyl-esters \u2192 packaged into <strong>chylomicrons<\/strong> \u2192 lymphatics \u2192 plasma.<\/li>\n\n\n\n<li>Chylomicron remnants (with apo B and apo E) are taken up by the <strong>liver<\/strong>, and vitamin A is stored in <strong>hepatic stellate cells<\/strong>.<\/li>\n\n\n\n<li><strong>50-85%<\/strong> of total body vitamin A is stored in the liver.<\/li>\n\n\n\n<li>Upon release, vitamin A circulates bound to <strong>retinol-binding proteins (RBPs)<\/strong>.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">FUNCTIONS<\/h2>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Vision<\/strong>:\n<ul class=\"wp-block-list\">\n<li>Necessary for <strong>retinal photoreceptor<\/strong> function (especially rod cells for night vision).<\/li>\n\n\n\n<li>Deficiency \u2192 decreased retinal 11-cis-retinol and rhodopsin, hence <strong>night blindness<\/strong> (nyctalopia).<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Epithelial Tissue<\/strong>:\n<ul class=\"wp-block-list\">\n<li>Involved in <strong>growth\/differentiation<\/strong> of epithelial cells.<\/li>\n\n\n\n<li>Deficiency \u2192 dryness (xerosis) and keratinization of mucosal surfaces (e.g., eyes).<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Bone Growth<\/strong>:\n<ul class=\"wp-block-list\">\n<li>Supports normal <strong>bone<\/strong> development.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Immune Function<\/strong>:\n<ul class=\"wp-block-list\">\n<li>Involved in maintaining <strong>immune competence<\/strong>.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">CLINICAL MANIFESTATIONS OF DEFICIENCY<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Night Blindness<\/strong> (nyctalopia): Earliest symptom of vitamin A deficiency.<\/li>\n\n\n\n<li><strong>Xerophthalmia<\/strong>: Progressive eye disorder with:\n<ul class=\"wp-block-list\">\n<li><strong>Xerosis<\/strong> (dryness of the conjunctiva)<\/li>\n\n\n\n<li><strong>Bitot spots<\/strong> (triangular grayish patches of keratinized epithelium on sclera)<\/li>\n\n\n\n<li><strong>Keratomalacia<\/strong> (corneal thinning) \u2192 can lead to perforation and blindness.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Other Symptoms<\/strong>:\n<ul class=\"wp-block-list\">\n<li><strong>Follicular hyperkeratosis<\/strong> on skin.<\/li>\n\n\n\n<li>Impaired bone growth.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">DIAGNOSIS<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Often due to <strong>inadequate dietary intake<\/strong> or <strong>malabsorption<\/strong>.<\/li>\n\n\n\n<li><strong>Serum vitamin A (retinol) level<\/strong> &lt;100 \u03bcg\/L indicates severe deficiency (normal reference range: ~325\u2013780 \u03bcg\/L in adults).<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">TREATMENT<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Severe deficiency (e.g., xerophthalmia)<\/strong>:\n<ul class=\"wp-block-list\">\n<li>High-dose therapy: ~60 mg of vitamin A immediately, then repeated 1 and 14 days later.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Milder deficiency (night blindness, Bitot spots)<\/strong>:\n<ul class=\"wp-block-list\">\n<li>Lower doses: ~3 mg daily for 3 months.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>Also address <strong>underlying causes<\/strong> (poor diet or malabsorption).<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">PREVENTION<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Recommended daily allowance<\/strong>:\n<ul class=\"wp-block-list\">\n<li>Men: 900 \u03bcg retinol\/day<\/li>\n\n\n\n<li>Women: 700 \u03bcg retinol\/day<\/li>\n\n\n\n<li>Pregnancy\/lactation: ~1.4 mg\/day<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>1 \u03bcg retinol = 12 \u03bcg \u03b2-carotene<\/strong>.<\/li>\n\n\n\n<li>Met by balanced diet rich in <strong>milk, eggs, fish, butter, yellow\/dark green vegetables<\/strong>.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>OVERVIEW oF VITAMIN A DEFICIENCY DIETARY SOURCES &amp; ABSORPTION FUNCTIONS CLINICAL MANIFESTATIONS OF DEFICIENCY DIAGNOSIS TREATMENT PREVENTION<\/p>\n","protected":false},"featured_media":0,"template":"","oen_topic_chapter":[689],"class_list":["post-4422619","oen_topic","type-oen_topic","status-publish","hentry","oen_topic_chapter-obesity-medicine"],"_links":{"self":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic\/4422619","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic"}],"about":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/types\/oen_topic"}],"version-history":[{"count":3,"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic\/4422619\/revisions"}],"predecessor-version":[{"id":4422623,"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic\/4422619\/revisions\/4422623"}],"wp:attachment":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/media?parent=4422619"}],"wp:term":[{"taxonomy":"oen_topic_chapter","embeddable":true,"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic_chapter?post=4422619"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}