• We measured plasma vitamin K concentrations in 194 5-day-old infants three hours after administration of a 4-mg dose of vitamin K (menaquinone-4, Kaytwo syrup, Eisai Co Ltd, Tokyo, Japan). We investigated association with other factors contributing to vitamin K deficiency. These plasma vitamin K concentrations varied greatly among the neonates from values below the limit of detection (2 ng/mL) to more than 1000 ng/mL. The vitamin K concentration was associated with nutritive vitamin K deficiency represented by plasma protein induced by vitamin K absence or antagonist-II (PIVKA-II) values. The wide variation in vitamin K absorption is considered to be one of the major causative factors in infantile vitamin K deficiency.
Shinzawa T, Mura T, Tsunei M, Shiraki K. Vitamin K Absorption Capacity and Its Association With Vitamin K Deficiency. Am J Dis Child. 1989;143(6):686–689. doi:10.1001/archpedi.1989.02150180064022
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