Vitamin K at birth

Vitamin K prophylaxis: leaving the old route for the new one?

Oral or parenteral administration of vitamin K is the accepted practice for prevention of early vitamin K deficiency bleeding (VKDB) in the newborn. However, vitamin K prophylaxis in the newborn continues to be a worldwide health concern, particularly in breastfed infants. This paper reviews the current status of the use of vitamin K for the prevention of early and late VKDB.

Vitamin K and childhood cancer: analysis of individual patient data from six case-control studies

To investigate the hypothesis that neonates who receive intramuscular vitamin K are at an increased risk of developing cancer, particularly leukaemia, a pooled analysis of individual patient data from six case-control studies conducted in Great Britain and Germany has been undertaken. Subjects comprised 2431 case children diagnosed with cancer before 15 years of age and 6338 control children. The retrospective assessment of whether or not an individual baby received vitamin K is not straightforward. In many cases no record was found in stored medical notes and two types of analysis were therefore conducted; in the first it was assumed that where no written record of vitamin K was found it had not been given, and in the second, where no written record of administration was found, information on hospital policy and perinatal morbidity was used to 'impute' whether or not vitamin K had been given. In the first analysis, no association was found between neonatal administration of intramuscular. vitamin K and childhood cancer: odds ratios adjusted for mode of delivery, admission to special care baby unit and low birth weight were 1.09 (95% confidence interval 0.92-1.28) for leukaemia and 1.05 (0.92-1.20) for other cancers. In the second analysis, the adjusted odds ratios increased to 1.21 (1.02-1.44) for leukaemia and 1.10 (0.95-1.26) for other cancers. This shift did not occur in all studies, and when data from the hypothesis generating Bristol study were excluded, the adjusted odds ratios for leukaemia became 1.06 (0.89-1.25) in the first analysis and 1.16 (0.97-1.39) when data on prophylaxis imputed from hospital policy and perinatal morbidity were used. We conclude that whilst the broad nature of the diagnostic groups and the poor quality of some of the vitamin K data mean that small effects cannot be entirely ruled out, our analysis provides no convincing evidence that intramuscular vitamin K is associated with childhood leukaemia.

Alpha1-antitrypsin deficiency with fatal intracranial hemorrhage in a newborn

A 4-week-old boy had a fatal intracranial hemorrhage resulting from vitamin K deficiency. The infant had received no vitamin K prophylaxis and was exclusively breastfed. At autopsy, examination of the liver showed cholestasis and fibrosis. DNA was isolated from a blood spot on a Gutherie sample card obtained from the infant for routine metabolic screening. This DNA was used for alpha1-antitrypsin genotyping studies. Genotyping studies identified homozygosity for the point mutation 9989G-->A, confirming a diagnosis of alpha1-antitrypsin deficiency (ZZ phenotype), and resulted in appropriate screening of siblings born after this child's death. Alpha1-antitrypsin deficiency should be considered in the differential diagnosis of infants with late hemorrhagic disease of the newborn. Use of blood from the metabolic screening card as a source of DNA allowed confirmation of this diagnosis after the infant's death.

Oral versus intramuscular phytomenadione: safety and efficacy compared

Oral and intramuscular phytomenadione (vitamin K1) prophylaxis became an issue following the report of a potential carcinogenic effect of intramuscular but not oral phytomenadione prophylaxis. There is increasing evidence, however, that oral phytomenadione prophylaxis is less effective for the prevention of late vitamin K deficiency bleeding (VKDB) than intramuscular prophylaxis. Following a report of an increased cancer risk after intramuscular phytomenadione, a series of papers on this issue appeared. Although an increased risk for solid tumours could almost certainly be excluded, a potential risk for acute lymphatic leukaemia in childhood could not be ruled out definitively. Almost all cases of late VKDB are preventable with intramuscular phytomenadione prophylaxis administered once at birth, whereas a single oral dose given at birth is much less effective. Repeated oral phytomenadione doses given to breast-fed infants either weekly (1 mg) or daily (25 microg) seem to be as effective as intramuscular phytomenadione prophylaxis. The efficacy of 3 oral 2mg doses with the new mixed micellar preparation ('Konakion MM') remains to be established. Although a number of studies have failed to confirm a cancer risk with phytomenadione, these studies have been unable to rule out a risk definitely because absence of evidence is not evidence of absence. A meta-analysis of the available studies might provide 95% confidence intervals narrow enough to exclude even a small cancer risk with some certainty. Oral prophylaxis will probably be as safe as the intramuscular prophylaxis if given daily (25 microg) or weekly (1 mg).

Prevention of vitamin K deficiency bleeding in newborns

Newborn babies are born vitamin K deficient; however, the deficiency is not sufficiently severe to cause a vitamin K deficiency coagulopathy and haemorrhagic disease of the newborn (HDN). Severe vitamin K deficiency can develop quickly in breast-fed newborns and can result in the appearance of classic HDN during the first week of life or late HDN during the first 2 months of life. Both forms of the disease can be severe, causing brain damage and death. Classic and late HDN are prevented by the intramuscular administration of vitamin K at birth. Oral prophylaxis prevents classic HDN but is ineffective in preventing late HDN. Despite proven effectiveness of intramuscular vitamin K prophylaxis there have been concerns about the need for, and safety of, this therapy. This review provides evidence that there is need for intramuscular vitamin K prophylaxis for all babies in order to eradicate haemorrhagic disease of the newborn and concludes that there is no evidence that this therapy is harmful.

Established antiepileptic drugs

Despite the recent entry into the market-place of a range of new pharmacological treatments for epilepsy, most patients still receive the standard antiepileptic drugs. This review considers the clinical place and practical use of these agents. Detailed consideration is given to carbamazepine, phenytoin, sodium valproate, phenobarbital and ethosuximide, with lesser emphasis on primidone, clobazam and clonazepam. Individualization of therapy, polypharmacy, refractory epilepsy, therapeutic drug monitoring, pregnancy, withdrawing treatment, epilepsy prophylaxis and referral to an epilepsy centre are also discussed. The paper concludes with a statement of 12 basic rules in prescribing established antiepileptic drugs.

Leukaemia and non-Hodgkin's lymphoma in children and young adults: are prenatal and neonatal factors important determinants of disease?

A medical record-based study of leukaemia and non-Hodgkin's lymphoma diagnosed before the age of 30 years was carried out at three hospitals in the south of England. Findings for 177 cases and 354 age- and sex-matched controls are presented here. For documented viral infection in pregnancy, the odds ratio (OR) was 6.0 [95% confidence interval (CI) 1.2-29.7] for leukaemia and infinity (95% CI 1.24-infinity) for non-Hodgkin's lymphoma. Mothers of leukaemic cases were more likely to be anaemic, the OR for a pregnancy haemoglobin below 10 g being 3.8 (95% CI 1.3-11.1). An association with birthweight was found for acute myeloid leukaemia, the OR for birthweights > 3500 g being 6.2 (95% CI 1.3-29.8). Further, the preceding siblings of those diagnosed with any form of leukaemia were also more likely to weigh > 3500 g at birth (OR 2.2; 95% CI 1.1-4.4). Overall, leukaemic cases appeared to be comparatively robust at birth with respect to other indicators of well-being, the ORs for jaundice, phototherapy, admission to special care nursery and neonatal intensive care all being less than 1.0. Further, no relation between childhood leukaemia and neonatal administration of intramuscular vitamin K was noted (OR 0.6, 95% CI 0.3-1.4; for acute lymphoblastic leukaemia diagnosed between the ages of 1 and 6 years).