Vitamin B6 (Pyridoxine)
Vitamin B6 (pyridoxine) refers to a group of water-soluble vitamins important in metabolic reactions via its active form, pyridoxal 5′-phosphate (PLP). PLP is involved in a number of enzymatic reactions: transammination reactions (such as by AST and ALT), decarboxylation reactions, and that of glycogen phosphorylase. PLP is involved neurotransmitter synthesis, histamine synthesis, hemoglobin synthesis and function, and gene expression. Given its important physiologic roles, a vitamin B6 deficiency can present with a number of signs and symptoms. Examples include neuropathy and paresthesias, convulsions, and a sideroblastic anemia secondary to ALA synthase dysfunction. It can be caused by a variety of reasons, notably by oral contraceptive or isoniazid use.