Affiliation:
1. Children's National Medical Center Department of Pulmonary Medicine Washington, DC
2. University of Maryland College of Agriculture Department of Nutrition and Food Science College Park Maryland
3. Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University Vitamin K Laboratory Boston Massachusetts U.S.A.
Abstract
Background:Patients with cystic fibrosis are at risk for impaired vitamin K status due to fat malabsorption from pancreatic insufficiency. This study was designed to assess vitamin K status and measure the effect of vitamin K1 supplementation in cystic fibrosis patients.Methods:Eighteen outpatients participated in a crossover study to determine the effect of vitamin K1 (phylloquinone) supplementation. After obtaining initial data, each subject was randomly assigned to either a 4‐week study treatment of 5 mg oral vitamin K1 supplementation per week, or no supplementation and then crossed over to the other treatment for a second 4 week period. Plasma, serum and urine samples were collected and analyzed pre‐study and at the end of each study period.Results:The mean concentration of plasma vitamin K1 for the supplemented group was significantly higher than the unsupplemented group, [0.34 nmol/L and 0.21 nmol/L, respectively (p < 0.05)]. The percent of undercarboxylated osteocalcin increased on supplementation from 17% to 31%, (p < 0.005). Prothrombin induced in vitamin K absence (PIVKA‐II) increased on supplementation from 5 ng/mL to 22 ng/mL, (p < 0.005). The ratio of urinary gammacarboxyglutamic acid/creatinine was similar for both study periods.Conclusions:In contrast to other studies in cystic fibrosis, this study demonstrated a need for vitamin K1 supplementation. The carboxylation state of osteocalcin and PIVKA‐II were the most sensitive indices of changes in vitamin K1 status. Although the 5 mg vitamin K1/week dose improved these vitamin K parameters, normal levels were not achieved.