Japanese fermented soybean food as the major determinant of the large geographic difference in circulating levels of vitamin K2: possible implications for hip-fracture risk.

Vitamin K deficiency bleeding (VKDB) in early infancy.

We conducted a systematic review to evaluate the burden of late vitamin K deficiency bleeding (VKDB) and the effect of vitamin K prophylaxis on the incidence of VKDB. We searched MEDLINE and other electronic databases, and included all observational studies including population surveys as well as randomized controlled trials (RCT). The median (interquartile range) burden of late VKDB was 35 (10.5 to 80) per 100 000 live births in infants who had not received prophylaxis at birth; the burden was much higher in low- and middle-income countries as compared with high-income countries-80 (72 to 80) vs 8.8 (5.8 to 17.8) per 100 000 live births. Two randomized trials evaluated the effect of intramuscular (IM) prophylaxis on the risk of classical VKDB. Although one trial reported a significant reduction in the incidence of any bleeding (relative risk (RR) 0.73, 95% confidence interval (CI) 0.56 to 0.96) and moderate to severe bleeding (RR 0.19, 0.08 to 0.46; number needed to treat (NNT) 74, 47 to 177), the other trial demonstrated a significant reduction in the risk of secondary bleeding after circumcision in male neonates (RR 0.18, CI 0.08 to 0.42; NNT 9, 6 to 15). No RCTs evaluated the effect of vitamin K prophylaxis on late VKDB. Data from four surveillance studies indicate that the use of IM/subcutaneous vitamin K prophylaxis could significantly reduce the risk of late VKDB when compared with no prophylaxis (pooled RR 0.02; 95% CI 0.00 to 0.10). When compared with IM prophylaxis, a single oral dose of vitamin K increased the risk of VKDB (RR 24.5; 95% CI 7.4 to 81.0) but multiple oral doses did not (RR 3.64; CI 0.82 to 16.3). There is low-quality evidence from observational studies that routine IM administration of 1 mg of vitamin K at birth reduces the incidence of late VKDB during infancy. Given the high risk of mortality and morbidity in infants with late VKDB, it seems appropriate to administer IM vitamin K prophylaxis to all neonates at birth. Future studies should compare the efficacy and safety of multiple oral doses with IM vitamin K and also evaluate the optimal dose of vitamin K in preterm neonates.

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Vitamin K prophylaxis for prevention of vitamin K deficiency bleeding: a systematic review.

The more recent introduction of techniques to assess vitamin K status is also leading to a deeper understanding of the nutritional and clinical role of vitamin K. Progress has been particularly rapid in the last decade and is the purpose of this annotation to review the advances in different areas

Vitamin K and vitamin K-dependent proteins.

Coagulation factors do not cross the placental barrier but are synthesized independently by the conceptus. At birth, activities of the vitamin K dependent factors II, VII, IX, and X and the concentrations of the contact factors XI and XII are reduced to about 50% of normal adult values. The levels of the factors V, VIII, XIII, and fibrinogen are similar to adult values. Plasma concentrations of the naturally occurring anticoagulant proteins (antithrombin, protein C, and protein S) are significantly lower at birth than during the adult years. Plasminogen is reduced by approximately 50%. Platelet counts are within the normal range, regarding function, however, neonatal platelets seem to be hyporeactive. The von Willebrand factor contains large multimers and its concentration is increased. Properties and functions of vitamin K as well as requirement and plasma concentrations in newborns are reviewed. Regarding vitamin K deficiency bleeding (VKDB), the classical nomenclature is used: "early" (presenting within the first 24 h of life), "classical" (day 1-7 after birth), and "late" (8 days to 6 months). After the presentation of the history of vitamin K prophylaxis, vitamin K levels are described as can be expected after the administration of prophylactic doses at various routes. Subsequently, the actual schedule of vitamin K prophylaxis as recommended by the "Osterreichische Gesellschaft fur Kinder- und Jugendheilkunde" is given as follows: i) the oral treatment of healthy full-term babies and orally fed preterm babies, ii) the parenteral treatment of small preterm and sick full-term babies, and iii) the treatment of mothers under medication with enzyme-inducing drugs with vitamin K during the last 15-30 days of pregnancy. The regimes of prophylactic vitamin K treatment of different countries are also given. Finally, the therapeutic use of vitamin K is addressed; the potential use of fresh-frozen plasma, prothrombin complex preparations, and recombinant factor VIIa is discussed.

The neonatal coagulation system and the vitamin K deficiency bleeding - a mini review.

Throughout Japan a total of 543 cases of vitamin K deficiency occurring in infants over 2 weeks of age were reported from January 1981 to June 1985. Of these cases, 427 showed no obvious reasons for vitamin K deficiency; this sort of case is known as “idiopathic vitamin K deficiency in infancy”. Another 57 cases had bleeding episodes due to vitamin K deficiency associated with obvious hepatobiliary lesions, chronic diarrhoea, long-term antibiotic therapy, etc; this sort is called “secondary vitamin K deficiency in infacy”. The third group, consisting of 59 cases, was made up of the socalled “near miss” type, in which a haemorrhagic tendency, without any obvious clinical haemorrhage, was discovered by Normotest, at the time of mass screening in most cases. In the idiopathic group, 269 cases (63.0%) developed bleeding episodes between the 1st and 2nd months of age, and 387 cases (90.0%) were entirely breast-fed. Intracranial baemorrhage was observed in 353 cases (82.7%) of this group. Moreover, slight elevation of serum transaminase and direct type bilirubin levels were observed in the idiopathic group. Liver dysfunction of unknown origin may play some role in the onset of vitamin K deficiency in infancy.

K. Sawada

Papers

The second nation-wide survey in Japan of vitamin K deficiency in infancy