title: Suboptimal vitamin K status despite supplementation in children and young adults with cystic fibrosis.
abstract: BACKGROUND
  For children and adolescents with cystic fibrosis (CF) and pancreatic insufficiency, the efficacy of routine vitamin K supplementation to normalize vitamin K status remains unclear.
  
  
  OBJECTIVE
  This study examined and determined predictors of vitamin K status in subjects aged 8-25 y with CF and pancreatic insufficiency taking various vitamin K supplements.
  
  
  METHODS
  In 97 subjects, serum 25-hydroxyvitamin D [25(OH)D], dietary intake, vitamin K supplement intake, and vitamin K statusmdashdetermined on the basis of the percentage of serum undercarboxylated osteocalcin (%ucOC; sufficient: lt 20%) and plasma proteins induced by vitamin K absence-factor II (PIVKA-II; n = 60; sufficient: le 2 microg/L)mdashwere assessed. The vitamin K supplementation groups were as follows: lt 150 microg/d (low; multivitamins or no supplement), 150-999 microg/d (middle; CF-specific vitamins), and ge 1000 microg/d (high; mephyton). %ucOC values were compared with 140 healthy subjects aged 6-21 y.
  
  
  RESULTS
  In subjects with CF, the median (range) %ucOC was 35% (3%, 76%) and the median (range) for PIVKA-II was 2 (0, 42) micro g/L. Subjects with CF had a higher %ucOC with low [45% (10%, 76%)] and medium [41% (3%, 66%)] supplement intakes but not with a high supplement intake [16% (4%, 72%)] compared with healthy subjects [23% (0%, 43%); both P lt 0.05]. Supplementation group for males and females and 25(OH)D and age for males were significant predictors of vitamin K status.
  
  
  CONCLUSIONS
  Vitamin K status was often suboptimal despite routine supplementation. Only subjects taking high-dose vitamin K achieved a status similar to healthy subjects, and only the vitamin K supplementation dose predicted vitamin K status for males and females. These data suggest that higher doses of vitamin K are required.
authors.affiliation: Department of Pediatrics, Children's Hospital of Philadelphia, PA 19104, USA. doughertyk@email.chop.edu
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Dougherty
authors.forename: Joan I
authors.initials: JI
authors.lastname: Schall
authors.forename: Virginia A
authors.initials: VA
authors.lastname: Stallings
mesh_terms: D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D003550:Cystic Fibrosis / Q000097:blood / Q000150:complications / Q000188:drug therapy*; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D008297:Male; D009752:Nutritional Status; D015675:Osteocalcin / Q000097:blood; D010182:Pancreatic Diseases / Q000150:complications / Q000188:drug therapy*; D011516:Prothrombin / Q000378:metabolism; D012737:Sex Factors; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014812:Vitamin K / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D014813:Vitamin K Deficiency / Q000188:drug therapy* / Q000209:etiology; D014815:Vitamins / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D055815:Young Adult
chemical_list: D014815:Vitamins; D015675:Osteocalcin; D014812:Vitamin K; D014807:Vitamin D; D011516:Prothrombin; C104450:25-hydroxyvitamin D