Znaczenie witaminy K w mukowiscydozie

Cystic fibrosis (CF) is the most common autosomal recessive genetic disease in Caucasians. CF is caused by a mutation in the CFTR gene (cystic fibrosis transmembrane conductance regulator), allocated on the long arm of chromosome 7. The product of this gene - CFTR protein - is a chloride on channel, which is found in the apical membrane of exocrine epithelial cells. CFTR mutations result in the lack of functional protein what leads to the accumulation of viscous mucus in many organs in the respiratory and gastrointestinal systems. CF patients are at high risk for developing vitamin K deficiency because of: fat malabsorption due to pancreatic exocrine insufficiency, liver diseases, the long-term use of antibiotics and resection of the small bowel for gastrointestinal complications such as meconium ileus. Vitamin K is a cofactor essential for posttranslational gamma-carboxylation of glutamic acid residues to form gamma-carboxyglutamic acid. Vitamin K-dependent proteins inlude the osteocalcin, proteins C, S, Z and procoagulation factors II, VI, IX, X. For this reason, vitamin K plays an important role in hemostasis and bone calcification. Its deficiency result in the appearance of undercarboxylated proteins, which are functionally defective. Therefore, these proteins serve as sensitive markers of vitamin K deficiency. CF patients are more prone to osteopenia, caused by chronic vitamin K shortage, than to coagulopathy. Available evidence suggests the need for its supplements.