{"id":24972,"date":"2025-07-31T12:14:59","date_gmt":"2025-07-31T11:14:59","guid":{"rendered":"https:\/\/apps.nhslothian.scot\/refhelp\/?page_id=24972"},"modified":"2025-08-04T09:33:26","modified_gmt":"2025-08-04T08:33:26","slug":"vitamin-b12-initial-tests-monitoring","status":"publish","type":"page","link":"https:\/\/apps.nhslothian.scot\/refhelp\/guidelines\/haematology\/vitamin-b12-deficiency\/vitamin-b12-initial-tests-monitoring\/","title":{"rendered":"Vitamin B12 -Initial tests &amp; monitoring"},"content":{"rendered":"\n<p><strong><u>Starting B12 treatment in those with macrocytosis +\/- anaemia<\/u><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>If the patient is anaemic or macrocytic<strong>&nbsp;request reticulocyte count<\/strong>&nbsp;and&nbsp;<strong>folate<\/strong>&nbsp;to help differentiate causes and as a baseline for assessing immediate response to treatment.<\/li>\n\n\n\n<li>Note that in severe B12 or folate deficiency, supplementation may cause <strong>severe hypokalaemia <\/strong>as red cell reproduction restarts and a U&amp;E check after starting treatment may be appropriate<\/li>\n\n\n\n<li>Check&nbsp;<strong>reticulocyte count&nbsp;<\/strong>again within&nbsp;<strong>7\u201310 days<\/strong>&nbsp;of starting treatment if initial haemoglobin and reticulocytes low.&nbsp; An increase in the reticulocyte count to above the normal range&nbsp;indicates that treatment is having a&nbsp;positive effect and red blood cell production is appropriately increasing<\/li>\n\n\n\n<li><strong>Repeat&nbsp;FBC&nbsp;and&nbsp;reticulocyte count&nbsp;at&nbsp;8 weeks.&nbsp;&nbsp;<\/strong>The mean cell volume (MCV) should be normalising, and reticulocyte count rising.&nbsp;If the reticulocyte count is still low, please see the <a href=\"https:\/\/apps.nhslothian.scot\/refhelp\/guidelines\/haematology\/macrocytosisisolated\/\" target=\"_blank\" rel=\"noreferrer noopener\">RefHelp macrocytosis guideline<\/a> as a haematology referral may be needed.<\/li>\n<\/ul>\n\n\n\n<p><strong>Example reticulocyte ranges:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Low&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &lt; 25 (often seen in low B12 \/ folate)<\/li>\n\n\n\n<li>Normal&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;25-85<\/li>\n\n\n\n<li>Raised&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &gt; 85<\/li>\n<\/ul>\n\n\n\n<p><strong><u>Vitamin B12 deficiency and immunological testing<\/u><\/strong><strong>.<\/strong><\/p>\n\n\n\n<p>Traditionally, two immunological tests have been associated with assessing B12 status, but they are both potentially problematic:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Intrinsic Factor antibody (IFAB)&nbsp;<\/strong>is poorly sensitive: IFAB may be absent in up to 40-50% of patients with pernicious anaemia, but positive IFAB is highly specific for pernicious anaemia.&nbsp;&nbsp;<\/li>\n\n\n\n<li><strong>Gastric Parietal Cell Antibodies<\/strong>&nbsp;are also not fully sensitive and are poorly specific so checking these is not always useful.&nbsp; Please note that if you do order gastric parietal cell antibodies, they form part of a linked test array, so your patient will automatically also be tested for anti-mitochondrial antibodies (AMA), Smooth muscle antibodies and LKM1 antibodies &#8211; which are all associated with autoimmune liver disease.<\/li>\n<\/ul>\n\n\n\n<p><em>In those who have low B12 levels, but no clear cause, the diagnosis of IFAB negative pernicious anaemia therefore relies on clinical evaluation<\/em> e.g. patients who fail to respond to oral B12 therapy following adequate replacement over at least 6 months (where IM B12 is not immediately indicated for other reasons).<br><br><em>In an individual where pre-test probability for pernicious anaemia is high (e.g. an older woman with a history of autoimmune diseases) a negative IF antibody result is more likely to be a false negative than in someone where pre-test probability is low (e.g. where there is an alternative explanation for B12 deficiency).&nbsp;<\/em><\/p>\n\n\n\n<p><strong>C.M &amp; A.K. 01-08-25<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Starting B12 treatment in those with macrocytosis +\/- anaemia Example reticulocyte ranges: Vitamin B12 deficiency and immunological testing. Traditionally, two immunological tests have been associated with assessing B12 status, but they are both potentially problematic: In those who have low B12 levels, but no clear cause, the diagnosis of IFAB negative pernicious anaemia therefore relies<\/p>\n","protected":false},"author":6,"featured_media":0,"parent":24957,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"categories":[1303],"class_list":["post-24972","page","type-page","status-publish","hentry","category-https-apps-nhslothian-scot-refhelp-vitamin-b12-initial-tests-monitoring"],"publishpress_future_workflow_manual_trigger":{"enabledWorkflows":[]},"rttpg_featured_image_url":null,"rttpg_author":{"display_name":"heatherlevy","author_link":"https:\/\/apps.nhslothian.scot\/refhelp\/author\/heatherlevy\/"},"rttpg_comment":0,"rttpg_category":" <a href=\"https:\/\/apps.nhslothian.scot\/refhelp\/category\/haematology\/https-apps-nhslothian-scot-refhelp-vitamin-b12-deficiency\/https-apps-nhslothian-scot-refhelp-vitamin-b12-initial-tests-monitoring\/\" rel=\"tag\">Vitamin B12-Initial-tests &amp; monitoring<\/a>","rttpg_excerpt":"Starting B12 treatment in those with macrocytosis +\/- anaemia Example reticulocyte ranges: Vitamin B12 deficiency and immunological testing. Traditionally, two immunological tests have been associated with assessing B12 status, but they are both potentially problematic: In those who have low B12 levels, but no clear cause, the diagnosis of IFAB negative pernicious anaemia therefore relies","_links":{"self":[{"href":"https:\/\/apps.nhslothian.scot\/refhelp\/wp-json\/wp\/v2\/pages\/24972","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/apps.nhslothian.scot\/refhelp\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/apps.nhslothian.scot\/refhelp\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/apps.nhslothian.scot\/refhelp\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/apps.nhslothian.scot\/refhelp\/wp-json\/wp\/v2\/comments?post=24972"}],"version-history":[{"count":3,"href":"https:\/\/apps.nhslothian.scot\/refhelp\/wp-json\/wp\/v2\/pages\/24972\/revisions"}],"predecessor-version":[{"id":24997,"href":"https:\/\/apps.nhslothian.scot\/refhelp\/wp-json\/wp\/v2\/pages\/24972\/revisions\/24997"}],"up":[{"embeddable":true,"href":"https:\/\/apps.nhslothian.scot\/refhelp\/wp-json\/wp\/v2\/pages\/24957"}],"wp:attachment":[{"href":"https:\/\/apps.nhslothian.scot\/refhelp\/wp-json\/wp\/v2\/media?parent=24972"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/apps.nhslothian.scot\/refhelp\/wp-json\/wp\/v2\/categories?post=24972"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}