{"id":24968,"date":"2025-07-31T11:37:12","date_gmt":"2025-07-31T10:37:12","guid":{"rendered":"https:\/\/apps.nhslothian.scot\/refhelp\/?page_id=24968"},"modified":"2025-08-04T09:33:51","modified_gmt":"2025-08-04T08:33:51","slug":"vitamin-b12-associated-medications-conditions","status":"publish","type":"page","link":"https:\/\/apps.nhslothian.scot\/refhelp\/guidelines\/haematology\/vitamin-b12-deficiency\/vitamin-b12-associated-medications-conditions\/","title":{"rendered":"Vitamin B12 &amp; associated medications\/conditions"},"content":{"rendered":"\n<p><strong><u>Metformin (for longer than 12 months)<\/u><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>No need to routinely check&nbsp;B12&nbsp;levels for those with diabetes on metformin but consider checking if potentially symptomatic or other risk factors for&nbsp;deficiency e.g. PPI or colchicine treatment, vegetarian \/ vegan diet, previous low&nbsp;B12&nbsp;levels and \/ or conditions associated with malabsorption e.g. post gastrectomy surgery, inflammatory bowel disease (<a href=\"https:\/\/www.gov.uk\/drug-safety-update\/metformin-and-reduced-vitamin-b12-levels-new-advice-for-monitoring-patients-at-risk\" target=\"_blank\" rel=\"noreferrer noopener\">MHRA guidance June 2022<\/a>).<\/li>\n\n\n\n<li>Usually improves with dietary improvement of B12 intake<\/li>\n\n\n\n<li>It has been suggested that an increased intake of calcium reverses the vitamin B12 malabsorption induced by metformin. Bauman WA et al, Diabetes Care 2000 (23) 1227-31<\/li>\n\n\n\n<li>Only assess B12 levels if objective evidence of deficiency is present including peripheral neuropathy or macrocytic anaemia. A FBC is included in the annual diabetes GP Order Comms (ICE) test request set, giving an additional safety net<\/li>\n\n\n\n<li>If low levels check IFAB and should be treated with a short course of OTC oral cyanocobalamin (50micrograms orally for 4 weeks). Response should be assessed clinically and continued if benefit is shown<\/li>\n\n\n\n<li>No need for prophylactic B12 administration.<\/li>\n<\/ul>\n\n\n\n<p><strong><u>Proton pump inhibitors and H2 antagonists<\/u><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>OTC oral replacement (25-100 micrograms orally) may be appropriate if objective evidence of deficiency is found<\/li>\n<\/ul>\n\n\n\n<p><strong><u>Anticonvulsants<\/u><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>If no objective features of B12 deficiency &#8211; no need for replacement<\/li>\n\n\n\n<li>OTC oral replacement (25-100 micrograms orally) may be appropriate if objective evidence of deficiency is found<\/li>\n<\/ul>\n\n\n\n<p><strong><u>Oral contraceptives and hormone replacement therapy<\/u><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Pregnancy and COCP cause altered B12 binding to plasma protein, so borderline \/ low levels are commonly seen, which may not indicate true deficiency<\/li>\n\n\n\n<li>Only assess B12 levels if objective symptoms develop and this is the only indication for treatment<\/li>\n\n\n\n<li>OTC oral replacement (25-100 micrograms orally) may be appropriate if objective evidence of deficiency is found<\/li>\n<\/ul>\n\n\n\n<p><strong><u>Colchicine<\/u><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Low levels can easily be increased with dietary supplementation<\/li>\n<\/ul>\n\n\n\n<p><strong><u>Antibiotics<\/u><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Low levels can easily be increased with dietary supplementation<\/li>\n<\/ul>\n\n\n\n<p><strong><u>Pregnancy<\/u><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Pregnancy and COCP cause altered B12 binding to plasma protein, so borderline\/low levels are commonly seen, which may not indicate true deficiency<\/li>\n\n\n\n<li>B12 is not routinely measured during pregnancy, therefore only test if symptoms develop (as per protocol above for non-pregnant patients)<\/li>\n\n\n\n<li>If pregnant or breastfeeding it is recommended that cyanocobalamin is prescribed rather than over-the-counter<\/li>\n<\/ul>\n\n\n\n<p><strong><u>Vegetarian and vegan diets<\/u><\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Vegetarians and vegans are at increased risk of B12 deficiency, especially during pregnancy and when breastfeeding.&nbsp;If relevant symptoms develop consider testing B12 levels, and oral supplementation may be required as per above protocol.&nbsp; If felt appropriate oral supplementation could be over the counter (NB: please provide the patient with instructions for what dose of cyanocobalamin to take as OTC supplements vary widely).&nbsp; However, if pregnant or breastfeeding it is recommended that cyanocobalamin is prescribed.<\/li>\n\n\n\n<li>Please see the <a href=\"https:\/\/www.vegansociety.com\/resources\/nutrition-and-health\/nutrients\/vitamin-b12\" target=\"_blank\" rel=\"noreferrer noopener\">Vegan Society advice<\/a>.<\/li>\n<\/ul>\n\n\n\n<p><strong>C.M &amp; A.K. 01-08-25<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Metformin (for longer than 12 months) Proton pump inhibitors and H2 antagonists Anticonvulsants Oral contraceptives and hormone replacement therapy Colchicine Antibiotics Pregnancy Vegetarian and vegan diets C.M &amp; A.K. 01-08-25<\/p>\n","protected":false},"author":6,"featured_media":0,"parent":24957,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"categories":[1302],"class_list":["post-24968","page","type-page","status-publish","hentry","category-https-apps-nhslothian-scot-refhelp-vitamin-b12-associated-medications-conditions"],"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-associated-medications-conditions\/\" rel=\"tag\">Vitamin B12 Associated medications &amp; conditions<\/a>","rttpg_excerpt":"Metformin (for longer than 12 months) Proton pump inhibitors and H2 antagonists Anticonvulsants Oral contraceptives and hormone replacement therapy Colchicine Antibiotics Pregnancy Vegetarian and vegan diets C.M &amp; A.K. 01-08-25","_links":{"self":[{"href":"https:\/\/apps.nhslothian.scot\/refhelp\/wp-json\/wp\/v2\/pages\/24968","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=24968"}],"version-history":[{"count":3,"href":"https:\/\/apps.nhslothian.scot\/refhelp\/wp-json\/wp\/v2\/pages\/24968\/revisions"}],"predecessor-version":[{"id":24998,"href":"https:\/\/apps.nhslothian.scot\/refhelp\/wp-json\/wp\/v2\/pages\/24968\/revisions\/24998"}],"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=24968"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/apps.nhslothian.scot\/refhelp\/wp-json\/wp\/v2\/categories?post=24968"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}