{"id":843,"date":"2020-02-17T22:21:38","date_gmt":"2020-02-17T16:51:38","guid":{"rendered":"https:\/\/medicineplexus.com\/?p=843"},"modified":"2020-02-17T22:21:38","modified_gmt":"2020-02-17T16:51:38","slug":"vitamin-b12","status":"publish","type":"post","link":"https:\/\/medicineplexus.com\/vitamin-b12\/","title":{"rendered":"Vitamin B12"},"content":{"rendered":"\n
Vitamin B12<\/strong><\/p>\n\n\n\n Dietary sources<\/em><\/p>\n\n\n\n Liver, kidney, sea fish, egg yolk. meat, cheese are the main vit B., containing constituents of diet.<\/p>\n\n\n\n The only vegetable source is legumes (pulses) which get it from microorganisms harboured in their root nodules.<\/p>\n\n\n\n Daily requirement <\/em>1- 3 \u03bcg, pregnancy and lactation 3-5 \u03bcg .<\/p>\n\n\n\n Metabolic functions<\/strong><\/p>\n\n\n\n Utilization of vit B12<\/strong><\/p>\n\n\n\n by gastric acid.<\/p>\n\n\n\n urine, because the plasma protein binding sites get saturated and free vit B12 is filtered at the glomerulus.<\/p>\n\n\n\n Deficiency <\/strong>occurs due to:<\/p>\n\n\n\n I. Addisonian pernicious anaemia<\/strong>: autoimmune disorder which results in destruction of gastric parietal cells<\/p>\n\n\n\n \u2022 absence of intrinsic factor in gastric juice (along with achlorhydria)<\/p>\n\n\n\n \u2022 inability to absorb B12<\/p>\n\n\n\n 2. Other causes of gastric mucosa! damage<\/strong>, e.g. chronic gastritis, gastric carcinoma, gastrectomy, etc.<\/p>\n\n\n\n 3. Malabsorption<\/strong> (damaged intestinal mucosa). Bowel resection, inflammatory bowel disease.<\/p>\n\n\n\n 4. Consumption of vit B12 by abnormal flora in intestine (blind loop syndrome) or fish tape worm<\/strong><\/p>\n\n\n\n 5. N<\/strong><\/em>utritional deficiency:<\/strong> less common \u00e0vegetarians.<\/p>\n\n\n\n 6. Increased demand:<\/strong> pregnancy. infancy.<\/p>\n\n\n\n Manifestations of deficiency are:<\/em><\/strong><\/p>\n\n\n\n (a) Megaloblastic anaemia<\/strong> \u00e0 generally the first manifestation), neutrophils ‘with hyper-segmented nuclei, giant platelets.<\/p>\n\n\n\n (b) Glossitis, g.i. disturbances:<\/strong> damage to epithelial structures.<\/p>\n\n\n\n (c) Neurological:<\/strong> subacute combined degeneration of spinal cord; peripheral neuritis- diminished vibration and position sense, paresthesias, depressed stretch reflexes. muscular weakness, ataxia; mental changes- poor memory, mood changes, hallucinations. ere. are late effects.<\/p>\n\n\n\n Preparations, dose, administration<\/strong><\/p>\n\n\n\n Because of higher protein binding and better retention in blood, hydroxocobalamin<\/strong> is preferred for parenteral administration<\/strong> to treat vit B 12 defi ciency.<\/p>\n\n\n\n The National list of essential medicines (2015) of India has included hydroxocobalamin in place of cyanocobalamin.<\/p>\n\n\n\n Prophylactic dose: <\/em><\/strong>3-10 \u03bcg\/day<\/strong> orally in those at risk of developing deficiency.<\/p>\n\n\n\n Therapeutic dose:<\/em><\/strong><\/em><\/p>\n\n\n\n Oral vit B12 is not dependable for treatment of confirmed vit B 12 deficiency because its absorption from the intestine is unreliable.<\/p>\n\n\n\n Injected vit B12 is a must when deficiency is due to lack of intrinsic factor (pernicious anaemia, other gastric causes),<\/p>\n\n\n\n since the absorptive mechanism is totally nonfunctional.<\/p>\n\n\n\n Hydroxocobalamin 1 mg i.m. daily or on alternate days for 2 weeks or till neurological symptoms (when<\/p>\n\n\n\n present) abate, followed by I mg injected every 1- 3 months for maintenance.<\/p>\n\n\n\n Uses<\/strong><\/p>\n\n\n\n It is wise to add 1- 5 mg of oral folic acid and an iron preparation, because reinstitution of brisk haemopoiesis may unmask deficiency of these factors. Response to vit B 12 is dramatic- symptomatic improvement starts in 2 days: appetite improves, patient feels better; mucosal lesions heal in 1- 2 weeks; reticulocyte count increases; Hb% and haematocrit start rising after 2 weeks; platelet count normalizes in 1O days and WBC count in 2-3 weeks.<\/p>\n\n\n\n Neurological parameters improve more slowly-may take several months. Full recovery \u00e06 months or more.<\/p>\n\n\n\n Adverse effects<\/strong><\/p>\n\n\n\n Even large doses \u00e0 are quite safe.<\/p>\n\n\n\n Allergic reactions have occurred on injection, probably due to contaminants.<\/p>\n","protected":false},"excerpt":{"rendered":" Vitamin B12 Cyanocobalamin and hydroxocobalamin are complex cobalt containing compounds present in the diet and referred to as vit B12. There is extrinsic factor (Vitamin B12)present in diet which combined with an intrinsic factor produced by stomach to give rise to the haemopoietic principle \u00e0 helped in its absorption. occurs as water soluble, thermostable red[…]\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"","_seopress_titles_title":"","_seopress_titles_desc":"","_seopress_robots_index":"","footnotes":""},"categories":[3],"tags":[],"_links":{"self":[{"href":"https:\/\/medicineplexus.com\/wp-json\/wp\/v2\/posts\/843"}],"collection":[{"href":"https:\/\/medicineplexus.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/medicineplexus.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/medicineplexus.com\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/medicineplexus.com\/wp-json\/wp\/v2\/comments?post=843"}],"version-history":[{"count":0,"href":"https:\/\/medicineplexus.com\/wp-json\/wp\/v2\/posts\/843\/revisions"}],"wp:attachment":[{"href":"https:\/\/medicineplexus.com\/wp-json\/wp\/v2\/media?parent=843"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/medicineplexus.com\/wp-json\/wp\/v2\/categories?post=843"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/medicineplexus.com\/wp-json\/wp\/v2\/tags?post=843"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}