Vitamin K-dependent coagulation parameters during the first six days of life: incidence of PIVKA II in newborns

Abnormal Prothrombin (PIVKA-II) Expression in Canine Tissues as an Indicator of Anticoagulant Poisoning

PIVKA-II is an aberrant form of vitamin K that has been demonstrated to be increased in human coagulation disorders and in some neoplastic diseases. In veterinary medicine, PIVKA-II levels have been demonstrated to be useful for distinguishing anticoagulant poisoning from other coagulopathies. In forensic pathology, there is the need to distinguish malicious poisoning from other causes of death and, in some cases, identifying poisoned dogs from dogs that died as a result of other coagulative disorders can be challenging. In this study, dogs that suddenly died underwent necropsy, histological examination, and toxicological analysis to establish cause of death. PIVKA-II immunohistochemical expression was evaluated on hepatic and renal tissues, and on neoplastic lesions when present. A total of 61 dogs were analyzed and anticoagulant substances were identified in 16 of the 61. Immunolabelling for PIVKA-II was observed in 27 of 61 cases in the liver and in 24 of 61 cases in the kidneys. Among the poisoned dogs, the PIVKA-II expression was present in the liver in 15 of 16 cases and in the kidneys in 16 of 16. Neoplastic lesions represented mainly by haemangiosarcomas were negative. This study highlights how the immunohistochemical expression of PIVKA-II in hepatic and renal tissues can be useful to identify patients with coagulative disorders due to clinical condition or the ingestion of anticoagulants substances.

Developmental haemostasis: secondary haemostasis

The haemostatic system is a complex interaction between the vasculature, cellular components and plasma proteins that interact to maintain haemostasis in the healthy body. The haemostatic system can be further defined as primary, secondary and tertiary haemostasis to better define the interdependent mechanisms that combine to maintain haemostasis. The term 'developmental haemostasis' was first introduced by Maureen Andrews in the 1980s to describe the age-related physiological changes of the coagulation system as it develops progressively over time from fetal, neonatal, paediatric to adult and geriatric systems. This paper will focus on developmental changes in secondary haemostasis, that is, the plasma protein changes that occur with age, particularly during the fetal and neonatal period, when the changes are most marked compared to the adult system.

The PIVKA II test: the first reliable coagulation test for autopsy investigations

To date there is no routinely used reliable diagnostic test that can be performed in the post-mortem period to investigate whether a deceased had a coagulation disorder. This paper describes a series of experiments to assess the use of an antigen-based method to investigate the vitamin K-dependent factor II function in the deceased. It illustrates that by using this approach the functional status of factor II can be investigated in the post-mortem period. The abnormal proteins that are investigated by this method appear to remain stable for at least 72 h and potentially up to at least 7 days. The method that is illustrated could thus be reliably used in the post-mortem period to identify a natural or drug-induced factor II abnormality. The potential for other protein components of the coagulation cascade to be investigated by similar antigen-based methodology is suggested.

Effect of a reduced vitamin K supplementation on prothrombin time in prematures and high-risk neonates

Recommendations for vitamin K supplementation were recently changed to 3 x 1 mg orally in healthy term neonates and 0.2 mg parenterally in prematures and high-risk neonates. Prothrombin times (PT) at reduced vitamin K doses (120 patients, 170 samples) during the first 6 weeks of life were below 40% in 6 patients only; all low PTs were unrelated to vitamin K. In the remaining patients, median PT was 100%; 79% of patients had values above 70%. PT was related to birthweight, gestational age and age. There was no decrease over the observation period. Following reduced oral and parenteral vitamin K regimens PTs were well within published reference values for neonates given larger amounts of vitamin K.