The symptoms of vitamin K deficiency include bleeding disorders, impaired bone development, and spontaneous rash.[1][2] The signs of vitamin K deficiency include biomarkers of vitamin K status, such as low serum concentrations of phylloquinone (vitamin K1) and PIVKA-II (protein induced by vitamin K absence or antagonist-II).[3][2] PIVKA-II is an incompletely carboxylated form of prothrombin, which is a key protein involved in blood coagulation that is carboxylated by vitamin K.[3][2]