title: Severe acquired vitamin K deficiency: a hypothesis for rapid response to therapy.
abstract: The potential mechanism underlying the rapid response to vitamin K replacement in acquired deficiency states is incompletely understood. To examine vitamin K metabolism, a 10-year-old boy with autoimmune enteropathy on oral vitamin K supplementation, who presented with profuse nosebleeds and calf tenderness, was evaluated. Laboratory analyses were consistent with severe vitamin K deficiency: vitamin K dependent protein (VKDP) levels < 5%, normal vitamin K epoxide level and depressed total prothrombin antigen (carboxylated and undercarboxyated forms). Intramuscular vitamin K (10 mg) was administered. Nine hours following therapy, VKDP levels corrected completely. Total prothrombin antigen increased indicating new prothrombin synthesis. However, the increase in the prothrombin-clotting assay far exceeded the increase in total prothrombin, supporting storage of undercarboxylated prothrombin in vitamin K deficiency states, with carboxylation and secretion after vitamin K replacement. Although this mechanism is known to occur in rodents, it has not been reported in humans. Our findings suggest a new potential mechanism of prothrombin metabolism in humans.
authors.affiliation: Department of Pathology, University of Vermont and Fletcher Allen Health Care, Burlington 05405, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Sakkinen
authors.forename: J D
authors.initials: JD
authors.lastname: Dickerman
authors.forename: R B
authors.initials: RB
authors.lastname: Colletti
authors.forename: J A
authors.initials: JA
authors.lastname: Sadowski
authors.forename: E A
authors.initials: EA
authors.lastname: Golden
authors.forename: E G
authors.initials: EG
authors.lastname: Bovill
mesh_terms: D001777:Blood Coagulation; D002648:Child; D006801:Humans; D008297:Male; D011516:Prothrombin; D014813:Vitamin K Deficiency / Q000097:blood
chemical_list: D011516:Prothrombin