Tehran University of Medical Sciences Frontiers in Emergency Medicine 2717-3593 7 4 2023 11 28 Veganism and hypercoagulable state-hyperhomocysteinemia presenting as pulmonary thrombo-embolism in a vegetarian living at high altitude e39 e39 Aarti Vaid Department of Internal Medicine, Postgraduate Institute of Medical Science and Research, Chandigarh-12, India Ashish Behera Department of Internal Medicine, Postgraduate Institute of Medical Science and Research, Chandigarh-12, India Navneet Sharma Department of Internal Medicine, Postgraduate Institute of Medical Science and Research, Chandigarh-12, India 2023 04 19 2023 10 03 Hyperhomocysteinemia as a hypercoagulable state has been debatable, but when associated with other highrisk factors like severe vitamin B12 and folate deficiency, smoking, high altitude, and antiphospholipid syndrome can present with thromboembolism. Vegans are at high risk of severe B12 deficiency as the primary source is animal products. Right now, the total number of vegans, vegetarians, and all related categories, is close to 14 per cent of the world population. We here present a young vegan with severe B12 deficiency presenting with sub-massive thromboembolism. https://fem.tums.ac.ir/index.php/fem/article/view/1200 https://fem.tums.ac.ir/index.php/fem/article/download/1200/459