Vitamin B12 deficiency and hyperhomocysteinemia: A description of two cases with thrombosis

Abstract

Elevated homocysteine levels are associated with venous and arterial thrombosis. This report describes two patients with low vitamin B12 levels due to pernicious anaemia and elevated homocysteine levels, one of whom presented with an arterial thrombosis (cerebrovascular event) and another with venous thrombosis (deep vein thrombosis) without any other apparent cause for their presentation. Although not routinely recommended, it may be of value to screen patients with unexplained arterial or venous thrombotic events for elevated homocysteine levels. However, the paradox remains, that while hyperhomocysteinemia is associated with an increased risk of thrombosis, therapeutic strategies that lower homocysteine levels do not reduce the risk of thrombotic events.