Donald R. Duerksen, MD FRCPC
Associate Professor of Medicine
St. Boniface General Hospital
Winnipeg, Mannitoba, Canada
CLINICAL IMPLICATIONS OF VITAMIN K CONTAINING MULTIVITAMINS IN PATIENTS RECEIVING PARENTERAL NUTRITION
In his review (TPN Therapy Today, Feb. 2005) Dr. Driscoll outlines the potential effects of inclusion of vitamin K in parenteral multivitamin preparations on home TPN patients and in particular the effects this may have on central venous catheter thrombosis. Individuals on home TPN may receive vitamin K from three different sources; diet, lipid emulsion, parenteral multivitamin preparations. The oral requirement of vitamin K has been estimated to be 1 mg/kg/day. Recently the Food and Nutrition Board of the National Academy of Sciences has established Dietary Reference Intakes (DRIs) and defined adequate intakes (AI) for macro and micronutrients.(1) For vitamin K, the AI has been estimated to be 120mg/day for men and 90mg/day for women. The bioavailability of vitamin K varies but may be as low as 20% (2) and therefore the IV requirement may be considerably lower than the oral requirement. Therefore patients receiving 150mg intravenously (as mandated by the FDA) will receive considerably greater amounts of this vitamin than recommended.
In addition, many patients will receive additional vitamin K from the lipid in their TPN and from their diet. Lipid emulsions contain 28.5-67.5 mg vitamin K per 100 ml of 20 % solution.(3;4) It has been demonstrated that this has a significant physiologic effect in hospitalized patients receiving TPN. The prevalence of prolonged INRs in patients receiving lipid based TPN, which has significant vitamin K content, is much less than in those receiving lipid emulsions with negligible vitamin K content.(5;6) Patients regularly ingesting foods with high vitamin K content and a lipid emulsion 3 times per week may consume well in excess of the AI for vitamin K.
