Review on Vitamin K Deficiency and its Biomarkers: Focus on the Novel Application of PIVKA-II in Clinical Practice.

Background: Vitamin K (VK) is a co-factor of the gamma-glutamyl carboxylase that catalyzes the conversion of glutamate residues to gamma-carboxyglutamate in VK-dependent proteins. The carboxylation reaction imparts the essential calcium-binding residues for the biological function of several proteins involved in the process of coagulation and bone metabolism. VK deficiency is frequently encountered in newborns and can lead to fatal hemorrhagic complications. This review describes and discusses the clinical application of VK deficiency testing. Methods: References and data were researched in PubMed and reviewed. Results: In adults, VK deficiency is associated with uncontrolled bleeding, liver dysfunction, osteoporosis, and coronary diseases. An improved understanding of the role of VK deficiency in health and illness can be achieved by setting a gold-standard in the inter-laboratory estimations of VK. However, conventional methods used to measure the VK deficiency based upon the coagulation time lack sensitivity and specificity. Recently, the alterations in proteins induced by VK absence or antagonism (PIVKA) have proven to be suitable biomarkers for detecting VK deficiency. The measurement of PIVKA-II exhibits an enhanced sensitivity and specificity in comparison to other methods conventionally used for the assessment of VK deficiency in newborns and adults. Conclusions: PIVKA-II could potentially be employed as an effective biomarker in the diagnosis of VK deficiency.