PIVKA-II correlates with INR but not protein C or protein S concentrations in cord blood among newborns

BACKGROUND: Protein induced by vitamin K absence (PIVKA)-II, inactive precursor of prothrombin, is elevated in vitamin K (VK) deficiency. Our aims were to find the prevalence of VK deficiency in neonates, assess the utility of international normalized ratio (INR) as a screening tool, and explore the relationship between PIVKA-II, activated partial thromboplastin time (aPTT) and VK dependent anticoagulants. METHODS: INR, aPTT, PIVKA-II, and proteins C and S activities were measured in neonatal cord blood prior to VK administration. RESULTS: We found 45 of neonates had subclinical VK deficiency based on PIVKA-II levels and 7 based on INR. Receiver operating characteristic (ROC) analysis assessed the utility of INR in detecting >4ng/mL of PIVKA-II and ROC of the area under the curve was 0.70 (95 CI 0.46-0.92, p=0.07). Proteins C and S activities were normal for age and did not correlate with PIVKA-II [(r=0.40, p=0.14) and (r=0.29, p=0.29), respectively]. There was no association between aPTT and PIVKA-II (p=0.83). CONCLUSION: PIVKA-II seems to be a sensitive indicator of mild VK deficiency. Further studies are needed to investigate the lack of relationship between PIVKA-II and functional protein C or S levels.