Vitamin K and the management of patients with cystic fibrosis.

OBJECTIVE: To assess the advisability of routine vitamin K supplementation in patients with cystic fibrosis (CF).

DATA SOURCES: Studies identified through a MEDLINE search with the use of MeSH terms vitamin K, cystic fibrosis, PIVKA-II (protein induced by vitamin K absence-II), coagulation abnormality and cystic fibrosis, and hepatic disorder and cystic fibrosis.

STUDY SELECTION: Six articles published between January 1981 and December 1992 were selected: one general review of vitamin K in infancy and five studies involving clinical trials of vitamin K supplementation or screening for fat-soluble vitamins, vitamin K or PIVKA-II in patients with CF. Review articles on nutrition in patients with CF, technical reports, letters, comments and case studies not bearing directly on these issues were excluded.

DATA EXTRACTION: Findings in these articles were analysed and compared to determine whether routine supplementation in all patients with CF is indicated, whether specific subgroups of these patients are susceptible to vitamin K deficiency and areas in which future research is needed.

RESULTS: There is no consensus on routine vitamin K supplementation in patients with CF. Studies have found a few cases of vitamin K deficiency among the population of people with CF. In addition, various factors--including pancreatic failure, liver disease, bowel resection and long-term use of antibiotics--can put some of these patients at risk of vitamin K deficiency.

CONCLUSIONS: Specific indications for routine vitamin K supplementation in all patients with CF have not yet been identified. Pending further studies, it would be prudent to consider routine supplementation in patients with CF and severe noncholestatic and cholestatic liver disease, major small-bowel resection, pancreatic insufficiency or lung disease necessitating frequent use of antibiotics. A stronger body of evidence is needed as a basis for clinical strategies.