Why do parents decline newborn intramuscular vitamin K prophylaxis?

OBJECTIVE

To explore the influencing factors and reasoning of parents who opt out of intramuscular vitamin K prophylaxis for their newborn.

DESIGN

We conducted a qualitative study with 15 families from the Otago/Southland region of New Zealand. Semistructured interviews explored their choice to opt out of intramuscular vitamin K prophylaxis and thematic analysis was used to elucidate themes that captured important aspects of this parental decision-making process.

RESULTS

Parents opt out of intramuscular vitamin K for a variety of reasons. These were clustered into three main themes: parents' beliefs and values (philosophy and spirituality), concerns about their child's welfare (pain and potential side effects) and external influencing factors (family, friends, media and health professionals). As part of a wider family hesitancy towards medical intervention, the majority of parents also raised concerns regarding other perinatal or childhood interventions.

CONCLUSION

Many factors influence parental decision making and lead to a decision to opt out of newborn intramuscular vitamin K prophylaxis. Due to strong parallels with other common childhood interventions, these findings have relevance for vitamin K prophylaxis and for other healthcare interventions in childhood.

The prevalence of coagulation abnormalities in hospitalized patients receiving lipid-based parenteral nutrition

BACKGROUND

Vitamin K is not a component of the multivitamin preparation added to parenteral nutrition (PN) solutions, and hospitalized patients receiving parenteral nutrition support are at risk of developing vitamin K deficiency.

METHODS

In this study, 84 consecutive patients receiving PN were followed up prospectively to determine the incidence of a raised international normalized ratio (INR). All patients received lipid in their PN, which contains approximately 30 microg of vitamin K/100 mL.

RESULTS

Patients were followed up for the course of PN or up to 4 weeks if they needed longer total parenteral nutrition. A raised INR compared with baseline developed in 3.6% of patients. All elevations were mild, and no patients developed clinical bleeding.

CONCLUSIONS

It may be unnecessary to routinely supplement patients with vitamin K if they are receiving a lipid emulsion containing significant amounts of vitamin K. For patients receiving warfarin therapy, it will be important for nutrition support services to be aware of the vitamin K content of the lipid emulsion they are using as patients receiving a multivitamin preparation containing vitamin K and lipid emulsion may receive increased amounts of vitamin K, which could lead to warfarin resistance.

A Mixed Micelle Formulation for Oral Delivery of Vitamin K

PURPOSE

To develop a stable micellar formulation of vitamin K for oral delivery, because the commercial and clinically used formulation of vitamin K (Konakion® MM) destabilizes at gastric pH resulting in low bioavailability of this vitamin in neonates with cholestasis.

METHODS

Mixed micelles composed of EPC, DSPE-PEG 2000 and glycocholic acid, with and without vitamin K, were prepared by a film hydration method. The influence of pH on the stability of the micelles was analyzed by dynamic light scattering (DLS). The critical micelle concentration (CMC) was determined by fluorescence spectroscopy using pyrene and the morphology was evaluated by transmission electron microscopy . Caco-2 cells were used to study the cytocompatibilty.

RESULTS

Mixed micelles with mean diameters from 7.1 to 11.0 nm and a narrow size distribution (PDI < 0.2) were obtained after 3 membrane extrusion cycles. Konakion® MM formed aggregated particles at gastric pH, which was avoided through steric stabilization by introducing PEG. TEM showed that mixed micelles had a spherical size (diameter of around 10 nm) with a narrow size distribution in agreement with the DLS results. The loading capacities for vitamin K of mixed micelles with varying molar fractions of DSPE-PEG and EPC (from 0/100 to 50/50 (mol/mol)) were 10.8-5.0 w%, respectively. The mixed micelles showed good cytocompatibility at concentrations of glycocholic acid between 0.12 and 1.20 mM.

CONCLUSIONS

Mixed micelles with superior stability to Konakion® MM at low pH were obtained by introducing DSPE-PEG 2000. These are therefore attractive oral formulations for vitamin K.

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 >4 ng/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.

Skin problems and EGFR-tyrosine kinase inhibitor

Epidermal growth factor receptor inhibition is a good target for the treatment of lung, colon, pancreatic and head and neck cancers. Epidermal growth factor receptor-tyrosine kinase inhibitor was first approved for the treatment of advanced lung cancer in 2002. Epidermal growth factor receptor-tyrosine kinase inhibitor plays an essential role in the treatment of cancer, especially for patients harbouring epidermal growth factor receptor activating mutation. Hence, skin toxicity is the most concerning issue for the epidermal growth factor receptor-tyrosine kinase inhibitor treatment. Skin toxicity is bothersome and sometimes affects the quality of life and treatment compliance. Thus, it is important for physicians to understand the background and how to manage epidermal growth factor receptor-tyrosine kinase inhibitor-associated skin toxicity. Here, the author reviewed the mechanism and upfront preventive and reactive treatments for epidermal growth factor receptor inhibitor-associated skin toxicities.

Effect of Vitamin K on Vascular Health and Physical Function in Older People with Vascular Disease--A Randomised Controlled Trial

BACKGROUND AND AIMS

Vitamin K insufficiency is common and linked to an increased risk of cardiovascular disease and osteoporotic fractures. The aim of this study was to examine whether daily supplementation with oral vitamin K could improve vascular health and physical function in older people with established vascular disease.

METHODS AND RESULTS

A double blind, randomised, placebo-controlled trial. Participants aged ≤ 70 years with a history of vascular disease were randomised to receive 6 months of daily oral 100mcg vitamin K2 (MK7 subtype) or matching placebo with outcomes measured at 0, 3 and 6 months. The primary outcome was between-group difference in endothelial function assessed using flow-mediated dilatation of the brachial artery at 6 months. Secondary outcomes included carotid-radial pulse wave velocity, augmentation index, blood pressure, carotid intima-media thickness, C-reactive protein, B-type natriuretic peptide, cholesterol and desphospho-uncarboxylated matrix Gla protein levels. Handgrip strength and the Short Physical Performance Battery assessed physical function, while postural sway was measured using a 3-dimensional force platform.

RESULTS

80 participants were randomised, mean age 77 (SD 5) years; 44/80 were male. Vitamin K levels rose in the intervention arm compared to placebo (+48 pg/ml vs -6 pg/ml, p=0.03) at 6 months. Desphospho-uncarboxylated Matrix Gla protein levels fell in the intervention group compared to placebo at 6 months (-130 [SD 117] pmol/L vs +13 [SD 180] pmol/L, p<0.001). No change was seen in endothelial function (between group difference -0.3% [95%CI -1.3 to 0.8], p=0.62). A modest, non-significant improvement in pulse wave velocity was seen in the vitamin K group (-0.8m/s [95%CI -1.8 to 0.3], p=0.15) while all other vascular and physical function outcomes unchanged.

CONCLUSIONS

Six months of vitamin K2 supplementation did not improve markers of vascular health or physical function in older patients with vascular disease.

Concepts and Controversies in Evaluating Vitamin K Status in Population-Based Studies

A better understanding of vitamin K's role in health and disease requires the assessment of vitamin K nutritional status in population and clinical studies. This is primarily accomplished using dietary questionnaires and/or biomarkers. Because food composition databases in the US are most complete for phylloquinone (vitamin K1, the primary form in Western diets), emphasis has been on phylloquinone intakes and associations with chronic diseases. There is growing interest in menaquinone (vitamin K2) intakes for which the food composition databases need to be expanded. Phylloquinone is commonly measured in circulation, has robust quality control schemes and changes in response to phylloquinone intake. Conversely, menaquinones are generally not detected in circulation unless large quantities are consumed. The undercarboxylated fractions of three vitamin K-dependent proteins are measurable in circulation, change in response to vitamin K supplementation and are modestly correlated. Since different vitamin K dependent proteins are implicated in different diseases the appropriate vitamin K-dependent protein biomarker depends on the outcome under study. In contrast to other nutrients, there is no single biomarker that is considered a gold-standard measure of vitamin K status. Most studies have limited volume of specimens. Strategic decisions, guided by the research question, need to be made when deciding on choice of biomarkers.

Reasons for Refusal of Newborn Vitamin K Prophylaxis: Implications for Management and Education

OBJECTIVE

The American Academy of Pediatrics recommends intramuscular (IM) vitamin K prophylaxis for all newborns to prevent vitamin K deficiency bleeding. Given the serious implications of late-onset vitamin K deficiency bleeding, our objective was to examine factors influencing parents' decisions to refuse IM vitamin K prophylaxis.

METHODS

Parents intending to refuse IM vitamin K prophylaxis at delivery were recruited from 5 community hospitals, 1 academic medical center, and 2 birthing centers in a single Southeastern state. Participants completed a written survey including demographics, birth and parenting decisions (eg, breastfeeding), and open-ended questions about their vitamin K information sources, concerns, and knowledge of risks.

RESULTS

The incidence of refusal was highest at the birthing centers. Fifty-four parents intending to refuse IM vitamin K completed the survey. Most were white (78%), over age 30 (57%), and college graduates (65%). All reported intention to exclusively breastfeed. Most refused hepatitis B vaccine (90%) and erythromycin eye ointment (77%). The most common source of information was the Internet (70%). Concerns included synthetic or toxic ingredients (37%), excessive dose (28%), and side effects (24%). Eighty-three percent of parents reported awareness of risks associated with vitamin K refusal. However, only 6 parents (11%) decided to accept IM prophylaxis.

CONCLUSIONS

This study provides an understanding of the concerns, mindset, and information sources used by parents refusing IM vitamin K. Educating parents about the importance of IM prophylaxis should begin in the prenatal period and must address concerns parents identify on the Internet.

Vitamins in pancreatic cancer: a review of underlying mechanisms and future applications

Although there is increasing evidence that vitamins influence pancreatic adenocarcinoma biology and carcinogenesis, a comprehensive review is lacking. In this study, we performed a PubMed literature search to review the anticancer mechanisms and the preclinical and clinical studies that support the development of the bioactive vitamins A, C, D, E, and K in pancreatic cancer intervention. Preclinical studies have shown promising results for vitamin A in pancreatic cancer prevention, with clinical trials showing intriguing responses in combination with immunotherapy. For vitamin C, preclinical studies have shown slower tumor growth rates and/or increased survival when used alone or in combination with gemcitabine, with clinical trials with this combination revealing decreased primary tumor sizes and improved performance status. Preclinical studies with vitamin D analogues have shown potent antiproliferative effects and repression of migration and invasion of pancreatic cancer cells, with a clinical trial showing increased time to progression when calciferol was added to docetaxel. For vitamin E, preclinical studies have shown that δ-tocotrienol and γ-tocotrienol inhibited tumor cell growth and survival and augmented gemcitabine activity. Early-phase clinical trials with δ-tocotrienol are ongoing. Vitamin K demonstrates activation of apoptosis and inhibition of cellular growth in pancreatic tumor cells; however, there are no clinical studies available for further evaluation. Although preclinical and clinical studies are encouraging, randomized controlled trials with endpoints based on insights gained from mechanistic and preclinical studies and early-phase clinical trials are required to determine the efficacy of bioactive vitamin interventions in pancreatic cancer.

Routine use of daily oral vitamin K to treat infants with cystic fibrosis

Vitamin K is routinely administered after birth in the UK to prevent haemorrhagic disease of the newborn. Despite this, vitamin K-deficient coagulopathy still occurs in infants with high morbidity and mortality. Up to 50% of late onset bleeding presents with intracranial haemorrhage. The risk of developing vitamin K coagulopathy is higher in infants with cystic fibrosis (CF) and those that are exclusively breast fed due to low vitamin K levels in breast milk and intestinal changes in bacterial flora. Oral vitamin K supplementation is a simple addition to routine CF treatment during infancy to prevent complications from significant coagulopathy.

Spontaneous Resolution of Chronic Subdural Haematoma in a Patient Receiving Anticoagulant Therapy

Significant chronic subdural hematoma (CSDH) is usually a surgical emergency. Spontaneous resolution of CSDH has rarely been reported in the literature. We are reporting a case of spontaneous resolution of CSDH in a patient receiving anticoagulant therapy who had undergone mitral valve replacement surgery.

[Bone and Nutrition. The association of vitamin K intake and bone health]

The association of vitamin K with bone mineral density has been reported in some previous cohort studies and intervention studies. In cohort studies, higher vitamin K1 intake was associated with lower fracture incidence. Some intervention studies have described that vitamin K1 and vitamin K2 (menaquinone-4 : MK-4) supplementation were modestly efficacious in preventing fracture, but not in preserving bone mass. Although dietary reference intake (adequate intake : AI) for vitamin K was increased from previous value, current AI was determined as the dose sufficient to maintain normal blood coagulation with little mentioning to bone. Vitamin K intake greater than the current AI would be required for the bone health.

[Bone and Nutrition. Nutritional management of osteoporosis]

Calcium intake was negatively associated with bone resorption marker such as DPD, NTX, and P1NP in Japanese postmenopausal osteoporotic patients. Not only to suppress bone resorption but also to keep higher hip bone mineral density were observed in the patients with higher intake of calcium than 800mg/day and higher vitamin D condition (more than 50nmol/L of serum 25 (OH) D). Higher calcium intake than 800mg/day from dairy and Tofu products, higher intake of vitamin D than 10μg/day from fish, and higher intake of vitamin K from vegetables should be recommended in Japanese postmenopausal osteoporotic patients. We should also pay attention to their losing weight and excess intake of these nutrients from supplements.

Association Between Vitamin K and the Metabolic Syndrome: A 10-Year Follow-Up Study in Adults

CONTEXT

The Metabolic Syndrome (MetS) is a cluster of metabolic abnormalities and is associated with increased risk of diabetes and cardiovascular diseases. Phylloquinone, menaquinones, and vitamin K status are associated with several components of MetS, but the association with MetS has hardly been studied to date.

OBJECTIVE

This study aimed to examine whether the intake and/or status of vitamin K is associated with MetS and its components.

DESIGN

This study comprised two cohorts, one of 402 women and one of 400 men (age 40-80 y). At followup 625 participants were still alive and willing to participate. Data were analyzed both cross sectionally and longitudinally with Poisson and linear regression adjusted for multiple confounders. Baseline phylloquinone/menaquinone intakes were measured with a validated food frequency questionnaire and vitamin K status with serum desphospho-uncarborxylated matrix-Gla protein level.

RESULTS

At baseline 270 (34.5%) participants had MetS and 171 (35.7%) at followup. Cross sectionally, high menaquinones intakes were associated (P(trend) = .08) with a lower prevalence of MetS with a prevalence ratio (PR) of 0.74 (95% confidence interval [CI], 0.54-1.03) for the highest vs the lowest tertile. At followup, the highest tertiles of menaquinones intake (PR = 0.62; 95% CI, 0.40-0.95) and vitamin K status (PR = 0.57; 95% CI, 0.38-0.87) were associated (P(trend) = .01) with a lower occurrence of MetS. These associations were mainly driven by relations with lower triacylglycerol concentrations for menaquinones and lower waist circumference for vitamin K status. Phylloquinone intake was not associated with MetS prevalence.

CONCLUSIONS

This study shows that a high intake of menaquinones and high vitamin K status are associated with a lower occurrence of MetS.

[Dental management of hemorrhage-prone patients]

The authors present a proposal of dental treatment and management of anticoagulated patients and of patients on antiplatelet therapy, with the approval by the Hungarian Association of Oral and Maxillofacial Surgeons and by the Dental Implantology Association of Hungarian Dentists. This current guide was based on recent Hungarian and on several foreign national guidelines and considers significant publications from international literature.

What Parents Need to Know About Vitamin K Administration at Birth

Prophylactic treatment of newborns with intramuscular vitamin K has been the standard of care for many years in the United States. However, instances of parental refusal of routine prophylaxis are currently on the rise. Refusal of routine prophylaxis can have serious long-term neurodevelopmental consequences for some newborns, who may subsequently develop vitamin K deficiency-associated hemorrhagic disease of the newborn (HDN).

Role of prophylactic vitamin K in preventing antibiotic induced hypoprothrombinemia

OBJECTIVE

To determine prophylactic role of single dose of vitamin K in prevention of antibiotic induced hypoprothrombinemia.

METHODS

This prospective comparative study included critically ill children in age group 2 mo to 12 y, admitted to a tertiary care hospital in India, likely to receive prolonged antibiotic therapy. One hundred twenty children, 60 in each group (A & B) were enrolled in the study. Patient allocation was done on alternate basis. Group A children received prophylactic vitamin K while group B did not. Baseline coagulation studies and other investigations were done in all children. Coagulation studies were repeated on day 10 and day 14 of antibiotic therapy and in between if required clinically. Children who developed deranged INR were given therapeutic vitamin K. If deranged INR returns to normal at 12 h of vitamin K administration then it indirectly confirms vitamin K deficiency. Analysis was done by fisher's t test and chi square test.

RESULTS

In children on prolonged antibiotic therapy, vitamin K deficiency was a common problem (15%). It was common in male sex, severe grade of protein energy malnutrition (PEM), N-methylthiotetrazole (NMTT) group containing antibiotics use and duration of antibiotic more than 10 d. It was same in children whether they received or did not receive prophylactic vitamin K on day 1 of antibiotic therapy (95% CI; p value 0.79).

CONCLUSIONS

Vitamin K deficiency is common problem in patients on prolonged antibiotic therapy. There is no role of single dose of prophylactic vitamin K in preventing antibiotic induced hypoprothrombinemia.

Synergistic effect of sorafenib and vitamin K on suppression of hepatocellular carcinoma cell migration and metastasis

Vitamin K plays a role in controlling cell growth. Anti-angiogenic effects of sorafenib lead to impairment of vitamin K uptake and induction of des-γ-carboxyprothrombin release by hepatocellular carcinoma (HCC) cells. We examined sorafenib and vitamin K individually and in combination regarding their ability to suppress migration and metastatic potential of HCC cells. HepG2 cells (HCC cell line) were treated with hepatocyte growth factor (HGF). E-Cadherin expression, phospho-MET (p-MET), and phospho-extracellular signal-regulated kinase (p-ERK) levels and cell migration were evaluated. HGF-stimulated HepG2 cells, which were treated with a combination of sorafenib and vitamin K, showed significantly increased expression of E-cadherin and impairment of migration ability compared to when treated with either agent alone. This combination therapy also induced marked inhibition of epithelial-mesenchymal transition phenotype; inhibition of HGF-stimulated cell proliferation, invasion and migration; and inhibition of HGF/c-MET signaling pathway. Levels of p-MET and p-ERK were also significantly reduced by this combination. Our experimental study demonstrated that sorafenib and vitamin K can function synergistically to inhibit the migration and proliferation of HCC cells. Combination therapy with sorafenib and vitamin K appears to be worthy of clinical trial with expectation of synergistic therapeutic effects.

The effect of preoperative vitamin K on the INR in bridging therapy

We investigated a bridging protocol using oral Vitamin K three days before scheduled surgery. 60 patients in two bridging protocols, 30 cases per protocol. The first cohort (Control group) had its warfarin held on Day-5 (five days before surgery). The intervention cohort (Vitamin K group) routinely received 2.5 mg of oral Vitamin K on Day-3 but was otherwise identically bridged. Primary outcome was INR on Day-1. Secondary outcomes included patients with INRs ≥1.5 on Day-1, bleeding episodes and elevated INR post surgery. Day-1 INR for the Vitamin K group was 1.16, vs. 1.28 for the Control group (p = 0.037). Postoperative INR was similar. Only the Control group had patients with INRs ≥1.5 on Day-1, or patients with significant bleeding. Adding Vitamin K on Day-3 leads to a safe preoperative INR and may limit other complications.

Vitamin K supplementation for cystic fibrosis

BACKGROUND

Cystic fibrosis is a genetic disorder which can lead to multiorgan dysfunction. Malabsorption of fat and fat-soluble vitamins (A, D, E, K) may occur and can cause subclinical deficiencies of some of these vitamins. Vitamin K is known to play an important role in both blood coagulation and bone formation. Supplementation with vitamin K appears to be one way of addressing the deficiency, but there is very limited agreement on the appropriate dose and frequency of use of these supplements.

OBJECTIVES

To assess the effects of vitamin K supplementation in people with cystic fibrosis and to determine the optimal dose and route of administration of vitamin K for both routine and therapeutic use.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Most recent search: 08 October 2014.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials of all preparations of vitamin K used as a supplement compared to either no supplementation (or placebo) at any dose or route and for any duration, in children or adults diagnosed with cystic fibrosis (by sweat test or genetic testing).

DATA COLLECTION AND ANALYSIS

Two authors independently screened papers, extracted trial details and assessed their risk of bias.

MAIN RESULTS

Two trials (total of 32 participants) each lasting one month were included in the review and were assessed as having a moderate risk of bias. One was a dose-ranging parallel group trial in children (aged 8 to 18 years); and the other (with an older cohort) had a cross-over design comparing supplements to no treatment, but no separate data were reported for the first intervention period. Neither of the trials addressed any of the primary outcomes (coagulation, bone formation and quality of life). Both trials reported the restoration of serum vitamin K and undercarboxylated osteocalcin levels to the normal range after one month of daily supplementation with 1 mg of vitamin K.

AUTHORS' CONCLUSIONS

Evidence from randomised controlled trials on the benefits of routine vitamin K supplementation for people with CF is currently weak and limited to two small trials of short duration. However, no harm was found and until further evidence is available, the present recommendations should be adhered to.

Measures of exposure impact genetic association studies: an example in vitamin K levels and VKORC1

Studies assessing the impact of gene-environment interactions on common human diseases and traits have been relatively few for many reasons. One often acknowledged reason is that it is difficult to accurately measure the environment or exposure. Indeed, most large-scale epidemiologic studies use questionnaires to assess and measure past and current exposure levels. While questionnaires may be cost-effective, the data may or may not accurately represent the exposure compared with more direct measurements (e.g., self-reported current smoking status versus direct measurement for cotinine levels). Much like phenotyping, the choice in how an exposure is measured may impact downstream tests of genetic association and gene-environment interaction studies. As a case study, we performed tests of association between five common VKORC1 SNPs and two different measurements of vitamin K levels, dietary (n=5,725) and serum (n=348), in the Third National Health and Nutrition Examination Studies (NHANES III). We did not replicate previously reported associations between VKORC1 and vitamin K levels using either measure. Furthermore, the suggestive associations and estimated genetic effect sizes identified in this study differed depending on the vitamin K measurement. This case study of VKORC1 and vitamin K levels serves as a cautionary example of the downstream consequences that the type of exposure measurement choices will have on genetic association and possibly gene-environment studies.

[Bleedings under NOAC (non Vitamin-K dependent oral anticoagulants). Evidence and practical management]

The doses of these drugs are barely tested and the potential clinical thromboembolic risk must be taken into account. Despite the widespread use of NOAC (non vitamin-K dependent oral anticoagulants) and recommendations of regulatory agencies and first consensus meeting on handling the bleeding situation under NOAC, especially in hospitals without a large hemostatic focus, uncertainty still exists. In case of mild bleeding from a clinical perspective, the medical care of these patients and the delay of the next dose or discontinuation is advised. A special laboratory analysis is indicated i.e. in case of known higher grade liver and kidney failure, which can cause a prolonged elimination of NOAC. The administration of factor concentrates is not indicated in this situation. In case of moderate to severe bleeding, the primary measures focus on the stabilization of the heart and circulatory function and parallel on the treatment depending on the localization of the bleeding source. According to experience, mostly gastrointestinal bleeding occurs under the NOAC, which should be supplied endoscopically. In life-threatening bleeding in addition to the measures of hemodynamic stabilization usually a special haemostasis management is required, which should be mainly clinically oriented. After the assessment of bleeding predictor, the time of the last dose and the dose of NOAC should be learned, but other causes of bleeding, including Fibrinolysis, should be excluded or treated. Subsequently, routinely promptly rivaroxaban and/or apixaban sensitive thromboplastin time (Quick's value) and a thrombin time (thrombin-poor calibrator) for qualitative assessment can be carried out because only very few hospitals have specific tests (anti-Xa measurements, bovine thrombin), which could be promptly done. If there is a significant deviation from the normal range or to present preliminary value of particular patient, an effect of NOAC most likely exists. In life-threatening bleeding the use of factor concentrates (procoagulants) is indicated. The first-line therapy should be PPSB. Only in exceptional cases, especially when dabigatran is taken, the use of aPPSB (FEIBA®) for prompt haemostasis can be considered. The haemostasis should be always clinically estimated and not according to coagulation tests. The use of rFVIIa (Novo Seven®) shows different results in the bleeding therapy (reversal) under Dabigatran. The doses of these drugs are barely tested and the potential clinical thromboembolic risk must be taken into account.

CONCLUSION

The current concepts of the newly developed antidotes are not clinically validated. First prospective, clinical registries have been started.

Vitamin K: dietary intake and requirements in different clinical conditions

PURPOSE OF REVIEW

Vitamin K is an enzyme cofactor for the carboxylation of vitamin K-dependent proteins. Functions include coagulation and regulation of calcification. Different clinical conditions may alter vitamin K requirements by affecting vitamin K status and vitamin K-dependent proteins carboxylation that are reviewed here.

RECENT FINDINGS

Vitamin K consumption greater than the current usual daily requirement to maintain health is indicated for prevention of vitamin K-deficient bleeding in infants and for rescue of over-anticoagulation in patients on vitamin K-dependent oral anticoagulants. Additional vitamin K intake may be required in malabsorptive conditions such as cystic fibrosis and following bariatric surgery. Carboxylation of vitamin K-dependent proteins occurs in multiple extrahepatic tissues and has been implicated in soft tissue calcification and insulin resistance, although the exact mechanisms have yet to be determined. Contribution of colonic flora to vitamin K requirements remains controversial.

SUMMARY

With the increased incidence of vitamin K-deficient bleeding and weight-loss surgical procedures, healthcare professionals need to monitor vitamin K status in certain patient populations. Future research on the roles of vitamin K in extrahepatic tissues as they pertain to chronic disease will provide insight into the therapeutic potential of vitamin K and lead to the development of recommendations for specific clinical populations.

Resveratrol, inositol, vitamin D and K in the prevention of cardiovascular and osteoporotic risk: a novel approach in peri- and postmenopause

The prevention of cardiovascular and osteoporotic risk is a topic of great importance in the peri- and postmenopausal periods. This paper reviews the role of resveratrol, inositol, vitamin D and K in the prevention of cardiovascular and osteoporotic risk in peri- and post-. The phytoestrogen-like activity of resveratrol has potential clinical implications in the gynecological practice. In particular transresveratrol inhibits low-density lipoprotein oxidation, which is a recognized risk factor for cardiovascular diseases. Resveratrol has also a documented antiplatelet effect and may prevent cardiovascular diseases inhibiting the cardiac fibroblasts proliferation. With regard to bone health, in in vitro studies resveratrol has shown activities in osteoblastic MC3T3-E1 cells. Resveratrol also interacts with vitamin D in promoting bone health. Resveratrol is considered a caloric restriction mimetic and potentially effects factors involved in the metabolic syndrome. Myo-inositol has documented in clinical studies its effectiveness in improving the metabolic syndrome in post menopausal women. Thus the supplementation with inositol and resveratrol may be useful in the prevention of insulin resistance and consequently metabolic syndrome and cardiovascular diseases risk. Finally vitamin K2 effects calcium metabolisms and subjects with higher levels of calcium in the bones tend to have a lower frequency of vascular calcifications and a lower cardiovascular risk. Vitamin K2 also has a key role in the bone homeostasis. A supplement including resveratrol, inositol, vitamin K and vitamin D offers a novel opportunity to the woman in peri- and postmenopause.

Impaired vitamin K recycling in uremia is rescued by vitamin K supplementation

In chronic kidney disease, vitamin K-dependent proteins, including the calcification inhibitor matrix Gla protein, are largely uncarboxylated indicating that functional vitamin K deficiency may contribute to uremic vascular calcification. Since the effects of uremia on the vitamin K cycle are unknown, we investigated the influence of uremia and vitamin K supplementation on the activity of the vitamin K cycle and extraosseous calcification. Uremia was induced in rats by an adenine-supplemented diet and vitamin K1 or K2 was administered over 4 and 7 weeks. After 4 weeks of adenine diet, the activity of the vitamin K cycle enzyme γ-carboxylase but not the activities of DT-diaphorase or vitamin K epoxide reductase were reduced. Serum levels of undercarboxylated matrix Gla protein increased, indicating functional vitamin K deficiency. There was no light microscopy-detectable calcification at this stage but chemically determined aortic and renal calcium content was increased. Vitamin K treatment reduced aortic and renal calcium content after 4 weeks. Seven weeks of uremia induced overt calcification in the aorta, heart, and kidneys; however, addition of vitamin K restored intrarenal γ-carboxylase activity and overstimulated it in the liver along with reducing heart and kidney calcification. Thus, uremic vitamin K deficiency may partially result from a reduction of the γ-carboxylase activity which possibly contributes to calcification. Pharmacological vitamin K supplementation restored the vitamin K cycle and slowed development of soft tissue calcification in experimental uremia.

Associations between intakes of individual nutrients or whole food groups and non-alcoholic fatty liver disease among Korean adults

BACKGROUND AND AIM

Dietary factors are closely associated with the risk of non-alcoholic fatty liver disease (NAFLD). Asian and Western diets differ in energy-nutrient composition, fatty-acid composition, and main nutritional sources; therefore, the implications would be limited if the Western-oriented study results were applied to Asian patients. We aimed to identify the nutrient and food group intakes of a typical Asian diet and assess their effects on NAFLD risk.

METHODS

In total, 348 subjects were recruited from 5 participating hospitals. Information on sociodemographic characteristics and health-related behaviors were obtained through face-to-face interviews. NAFLD was diagnosed by ultrasound. Dietary intakes were assessed with a 24-h recall applying a multiple-pass approach and 4-day food records that included 1 or 2 weekend days.

RESULTS

There were no significant differences in health-related behaviors between the cases and controls except for smoking behavior. The cases had elevated triacylglycerol, fasting glucose, and low-density lipoprotein cholesterol levels compared with the controls. In men, after adjusting for variables, low intakes of vitamin C (odds ratio [OR], 4.23), vitamin K (OR, 3.93), folate (OR, 3.37), omega-3 fatty acids (OR, 2.16), and nuts and seeds (OR, 3.66) were associated with a significantly higher risk for developing NAFLD. In women, vitamin K (OR, 2.54) and vegetable (OR, 4.11) intakes showed a significant beneficial effect for lowering NAFLD risk.

CONCLUSIONS

Adequate intakes of vitamin C, vitamin K, folate, omega-3 fatty acids, nuts and seeds, and vegetables may help in preventing NAFLD in Korean adults.

Vitamin K for improved anticoagulation control in patients receiving warfarin

BACKGROUND

Effective use of warfarin involves keeping the international normalised ratio (INR) within a relatively narrow therapeutic range. However, patients respond widely to their dose of warfarin. Overcoagulation can lead to an increased risk of excessive bleeding, while undercoagulation can lead to increased clot formation. There is some evidence that patients with a variable response to warfarin may benefit from a concomitant low dose of vitamin K.

OBJECTIVES

To assess the effects of concomitant supplementation of low-dose oral vitamin K for anticoagulation control in patients being initiated on or taking a maintenance dose of warfarin.

SEARCH METHODS

To identify previous reviews, we searched the Database of Abstracts of Reviews of Effects (DARE via The Cochrane Library, Wiley) (Issue 2, 2011). To identify primary studies, we searched the Cochrane Central Register of Controlled Trials (CENTRAL via The Cochrane Library, Wiley) (Issue 2, 2014), Ovid MEDLINE (R) In-Process & Other Non-Indexed Citations database and Ovid MEDLINE (R) (OvidSP) (1946 to 25 February 2014), Embase (OvidSP) (1974 to week 8 of 2014), Science Citation Index Expanded™ & Conference Proceedings Citation Index - Science (Web of Science™) (1945 to 27 February 2014), and the NHS Economics Evaluations Database (NHS EED) (via The Cochrane Library, Wiley) (Issue 2, 2014). We did not apply any language or date restrictions. We used additional methods to identify grey literature and ongoing studies.

SELECTION CRITERIA

Randomised controlled trials comparing the addition of vitamin K versus placebo in patients initiating warfarin or already taking warfarin.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected and extracted data from included studies. When disagreement arose, a third author helped reached a consensus. We also assessed risk of bias.

MAIN RESULTS

We identified two studies with a total of 100 participants for inclusion in the review. We found the overall risk of bias to be unclear in a number of domains. Neither study reported the time taken to the first INR in range. Only one study (70 participants) reported the mean time in therapeutic range as a percentage. This study found that in the group of participants deemed to have poor INR control, the addition of 150 micrograms (mcg) oral vitamin K significantly improved anticoagulation control in those with unexplained instability of response to warfarin. The second study (30 participants) reported the effect of 175 mcg oral vitamin K versus placebo on participants with high variability in their INR levels. The study concluded that vitamin K supplementation did not significantly improve the stability of anticoagulation for participants on chronic anticoagulation therapy. However, the study was only available in abstract form, and communication with the lead author confirmed that there were no further publications. Therefore, we interpreted this conclusion with caution. Neither study reported any thromboembolic events, haemorrhage, or death from the addition of vitamin K supplementation.

AUTHORS' CONCLUSIONS

Two included studies in this review compared whether the addition of a low dose (150 to 175 mcg) of vitamin K given to participants with a high-variability response to warfarin improved their INR control. One study demonstrated a significant improvement, while another smaller study (published in abstract only) suggested no overall benefit. Currently, there are insufficient data to suggest an overall benefit. Larger, higher quality trials are needed to examine if low-dose vitamin K improves INR control in those starting or already taking warfarin.

[Monitoring options and reversal agents for oral anticoagulants]

The approval of the oral direct thrombin inhibitor dabigatranetexilat and the oral factor Xa inhibitors rivaroxaban and apixaban as thromboprophylaxis challenges the position of the vitamin K antagonists (VKA). Predictable pharmacodynamics gives the new oral anticoagulants an advantageous profile. Unlike VKAs there is no specific reversal agent available for the new oral anticoagulants. Experience with haemostatic products for the emergency management of critical bleeding caused by these agents is limited.

Vitamin K status in healthy volunteers

Vitamin K's recommended dietary allowance (RDA) is based on the hepatic requirement for clotting factor synthesis, but substantial concentrations of undercarboxylated extra-hepatic Gla-proteins are found in the circulation of non-supplemented individuals. This suggests that vitamin K intake above the RDA is required for an optimal extra-hepatic vitamin K status. Circulating uncarboxylated osteocalcin (ucOC) and desphospho-uncarboxylated matrix Gla-protein (dp-ucMGP) are considered markers of the vitamin K status in bone and the vasculature, respectively. We measured these markers in 896 samples of healthy volunteers and defined target groups for vitamin K supplementation based on increased levels indicative of tissue-specific vitamin K deficiency. We studied the response to vitamin K supplements at different states of vitamin K deficiency by measuring the circulating dp-ucMGP level in samples from two short-term trials on menaquinone-7 (MK-7, vitamin K2) supplementation in 42 children and 68 adults. Children had high ucOC levels (3.4-96.9 ng ml(-1)); other age groups had values in the range of 1.5-5.0 ng ml(-1). From the age of 40 years, dp-ucMGP levels gradually increased. Children and adults with more pronounced vitamin K deficiency gave the highest responses to MK-7 supplementation. Children and adults above 40 years showed the largest tissue-specific vitamin deficiency and accordingly may benefit from MK-7 supplementation to improve their extra-hepatic vitamin K status.

Prediction of optimal warfarin maintenance dose using advanced artificial neural networks

BACKGROUND

In recent years, pharmacogenetic algorithms were developed for estimating the appropriate dose of vitamin K antagonists.

AIM

To evaluate the performance of new generation artificial neural networks (ANNs) to predict the warfarin maintenance dose.

METHODS

Demographic, clinical and genetic data (CYP2C9 and VKORC1 polymorphisms) from 377 patients treated with warfarin were used. The final prediction model was based on 23 variables selected by TWIST® system within a bipartite division of the data set (training and testing) protocol.

RESULTS

The ANN algorithm reached high accuracy, with an average absolute error of 5.7 mg of the warfarin maintenance dose. In the subset of patients requiring ≤21 mg and 21-49 mg (45 and 51% of the cohort, respectively) the absolute error was 3.86 mg and 5.45 with a high percentage of subjects being correctly identified (71 and 73%, respectively).

CONCLUSION

ANN appears to be a promising tool for vitamin K antagonist maintenance dose prediction.

Exercise, nutrition and managing hip fracture in older persons

PURPOSE OF REVIEW

Lifestyle factors play a role in both the genesis and recovery from fragility fracture. The purpose of this review is to summarize recent evidence for exercise and nutrition in the management of hip fracture.

RECENT FINDINGS

Recent randomized controlled trials of exercise have primarily consisted of isolated resistance training or multimodal home-based programs. More robust, long-term, or supervised training is generally associated with greater clinical benefits, including muscle strength, mobility, and function. Recent nutritional interventions have included multinutrient supplements, nutritional counseling and support, and vitamin D/calcium supplementation. Isolated nutritional interventions have not consistently shown significant impact on long-term outcomes after hip fracture, although improvements in body weight, biochemical indices, complication rates, and mobility have been reported. Overall, there is marked heterogeneity in the robustness of responses seen to hip fracture treatment studies. Few large, long-term, multicomponent interventions with clinically relevant outcomes of functional independence, need for residential care, mortality, and quality of life have been reported.

SUMMARY

Evidence-based approaches to hip fracture should include comprehensive risk-factor assessment and treatment for sarcopenia/dynapenia, balance impairment, undernutrition of protein, energy, vitamin D and calcium, depression, cognitive impairment, sensory impairment, social isolation, and comorbid illness with exercise, nutrition and other modalities.

Fast-food and full-service restaurant consumption in relation to daily energy and nutrient intakes among US adult cancer survivors, 2003-2012

BACKGROUND

Healthy diet is an essential component in cancer survivorship care planning. Cancer survivors should be particularly prudent regarding their daily food choices, with an aim of ensuring safe consumption, reducing risk of recurrence or other comorbidity, and improving quality of life.

OBJECTIVE

We aimed to examine the impacts of fast-food and full-service restaurant consumption on daily energy and nutrient intakes among US adult cancer survivors.

METHODS

Nationally representative data of 1308 adult cancer survivors came from the National Health and Nutrition Examination Survey 2003-2012 waves. First-difference estimator was adopted to address confounding bias from time-invariant unobservables like personal food/beverage preferences by using within-individual variations in diet and restaurant consumption status between two non-consecutive 24-hour dietary recalls.

RESULTS

Fast-food and full-service restaurant consumption, respectively, was associated with an increase in daily total energy intake by 125.97 and 152.26 kcal and sodium intake by 312.47 and 373.75 mg. Fast-food consumption was significantly associated with a decrease in daily vitamin A intake by 119.88 µg and vitamin K intake by 30.48 µg, whereas full-service restaurant consumption was associated with an increase in daily fat intake by 8.99 g and omega-6 fatty acid intake by 3.85 g, and a decrease in vitamin D intake by 0.93 µg. Compared with fast-food and full-service restaurant consumption at home, consumption away from home led to further reduced diet quality.

CONCLUSIONS

Individualized nutrition counseling and food assistance programs should address cancer survivors' overall dining-out behavior rather than fast-food consumption alone.

Menaquinones, bacteria, and the food supply: the relevance of dairy and fermented food products to vitamin K requirements

Vitamin K exists in the food supply as phylloquinone, a plant-based form and as menaquinones (MKs), a collection of isoprenologues mostly originating from bacterial synthesis. Although multiple bacterial species used as starter cultures for food fermentations synthesize MK, relatively little is known about the presence and distribution of MK in the food supply and the relative contribution of MK to total dietary vitamin K intake. Dairy products may be a predominant source of dietary MK in many regions of the world, and there is recent interest in enhancing the MK content of dairy products through identification and selection of MK-producing bacteria in dairy fermentations. This interest is increased by emerging evidence that current dietary recommendations based on the classic role of vitamin K as an enzyme cofactor for coagulation proteins may not be optimal for supporting vitamin K requirements in extrahepatic tissues and that MK may have unique bioactivity beyond that as an enzyme cofactor. Observational studies have reported favorable associations between MK intake and bone and cardiovascular health. Although randomized trials have provided some evidence to support the beneficial effects of MK on bone, the evidence to date is not definitive, and randomized trials have not yet examined MK intake in relation to cardiovascular outcomes. Food production practices provide a means to enhance dietary MK availability and intake. However, parallel research is needed to optimize these production practices, develop comprehensive food MK content databases, and test hypotheses of unique beneficial physiological roles of MK beyond that achieved by phylloquinone.

Treatment with vitamin K in hip fracture patients receiving warfarin

BACKGROUND

Hip fractures are common in the elderly population, but surgical treatment of these fractures within the first 48 hours decreases morbidity and mortality. The management of patients with hip fracture requiring surgery who are taking warfarin anticoagulation is unclear.

OBJECTIVES

To determine the effect of vitamin K on hip fracture patients treated with warfarin.

METHODS

We retrospectively examined the management of 21 patients with hip fractures who were being treated with warfarin at the time of admission. Vitamin K was given to 11 of the 21 patients. A third group, which served as a control, consisting of 35 hip fracture patients who were not being treated with anticoagulants was also evaluated.

RESULTS

Patients who received vitamin K took fewer days to reach target international normalized ratio (INR) (1.73 +/- 0.90 vs. 4.30 +/- 1.89, P < 0.001) and had less preoperative time (2.64 +/- 1.12 vs. 5.10 +/- 2.42 days, P < 0.008) when compared with patients who did not receive vitamin K. In addition, these patients had statistically significantly shorter hospitalization stays (9.4 +/- 1.9 and 13.2 +/- 4.9 days, one-sided P < 0.06). There was no difference in the amount of blood found in the wound drains (111.8 +/- 68.5 vs. 103.0 +/- 69.4 ml) or the number of blood units administered (1.45 +/- 1.29 vs. 2.00 +/- 2.75 units).

CONCLUSIONS

Treatment with vitamin K for hip fracture patients who receive warfarin shortens preoperative time, reduces the length of hospitalization and probably reduces morbidity and mortality.

Vitamin K supplementation for cystic fibrosis

BACKGROUND

Cystic fibrosis is a genetic disorder which can lead to multiorgan dysfunction. Malabsorption of fat and fat-soluble vitamins (A, D, E, K) may occur and can cause subclinical deficiencies of some of these vitamins. Vitamin K is known to play an important role in both blood coagulation and bone formation. Supplementation with vitamin K appears to be one way of addressing the deficiency, but there is very limited agreement on the appropriate dose and frequency of use of these supplements.

OBJECTIVES

To assess the effects of vitamin K supplementation in people with cystic fibrosis and to determine the optimal dose and route of administration of vitamin K for both routine and therapeutic use.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Most recent search: 11 October 2012.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials of all preparations of vitamin K used as a supplement compared to either no supplementation (or placebo) at any dose or route and for any duration, in children or adults diagnosed with cystic fibrosis (by sweat test or genetic testing).

DATA COLLECTION AND ANALYSIS

Two authors independently screened papers, extracted trial details and assessed their risk of bias.

MAIN RESULTS

Two trials (total of 32 participants) were included in the review and were assessed as having a moderate risk of bias. One was a dose-ranging parallel group trial; and the other had a cross-over design, but no separate data were reported for the first intervention period. Neither of the trials addressed any of the primary outcomes (coagulation, bone formation and quality of life). Both trials reported the restoration of serum vitamin K and undercarboxylated osteocalcin levels to the normal range after one month of daily supplementation with 1 mg of vitamin K.

AUTHORS' CONCLUSIONS

Evidence from randomised controlled trials on the benefits of routine vitamin K supplementation for people with CF is currently weak and limited to two small trials of short duration. However, no harm was found and until further evidence is available, the present recommendations should be adhered to.

Effect of a Triphasic Oral Contraceptive on Drug-Metabolizing Enzyme Activity as Measured by the Validated Cooperstown 5+1 Cocktail

The effects of a common oral contraceptive preparation on the activity of 7 drug-metabolizing enzymes were investigated using the validated Cooperstown 5+1 Cocktail. In a randomized crossover fashion, 10 premenopausal women received caffeine, dextromethorphan, omeprazole, intravenous midazolam, and warfarin + vitamin K with and without a triphasic oral contraceptive (ethinyl estradiol 35 microg) and varying doses of daily norgestimate (0.18, 0.215, and 0.25 mg). Bioequivalence testing showed nonequivalence in drug versus no-drug treatment on the activity of drug-metabolizing enzymes (as reflected by metabolite ratios following probe drug administration); the activity of CYP1A2, CYP2C19, and NAT-2 decreased following the oral contraceptive, whereas the activity of CYP2C9 and CYP2D6 increased. No effects on xanthine oxidase or hepatic CYP3A were seen. Application of a non-parametric statistical testing approach revealed a significant difference only for CYP1A2 and CYP2C19. This triphasic oral contraceptive may have a clinically significant effect on the activity of some drug-metabolizing enzymes.

[Diagnosis and treatment of warfarin resistance]

Warfarin resistance is a phenomenon that patients need to take much higher than normally prescribed dosage of warfarin to maintain the target therapeutic international normalized ratio (INR) range, or even fail to reach the target INR. Warfarin resistance can be categorized in etiologic terms as hereditary vs acquired, or in pharmacologic terms as pharmacokinetic vs pharmacodynamic. Once warfarin resistance is diagnosed, the type of resistance should be determined as soon as possible so that treatment could be oriented toward the causes. Poor compliance, genetic mutations, concurrent medications that could decrease the absorption or increase the clearance of warfarin, and consumption of diet rich in vitamin K are the major reasons for warfarin resistance. Educating patients, increasing warfarin dosage and switching to other anticoagulants would be effective for warfarin resistance.

[Prevention and treatment of major bleeding during anticoagulation]

To prevent major hemorrhage during anticoagulation, it is quite important to manage controllable risk factors such as hypertension, diabetes mellitus, smoking habit, and too much alcohol intake. It is also important to avoid dual antithrombotic therapy as long as possible, which increases severe bleeding events. For patients with major bleeding during anticoagulation, we should stop oral medication, stop bleeding by mechanical compression or surgical interventions, and maintain circulation blood volume and blood pressure by appropriate intravenous drip infusion. When intracranial hemorrhage happens, adequate treatment to suppress blood pressure should be provided. Administration of prothrombin complex concentrate (PCC) and vitamin K is effective for urgent reversal of anticoagulation by warfarin. The PCC may be also useful for that by novel oral anticoagulants.

Positive selection in the chromosome 16 VKORC1 genomic region has contributed to the variability of anticoagulant response in humans

VKORC1 (vitamin K epoxide reductase complex subunit 1, 16p11.2) is the main genetic determinant of human response to oral anticoagulants of antivitamin K type (AVK). This gene was recently suggested to be a putative target of positive selection in East Asian populations. In this study, we genotyped the HGDP-CEPH Panel for six VKORC1 SNPs and downloaded chromosome 16 genotypes from the HGDP-CEPH database in order to characterize the geographic distribution of footprints of positive selection within and around this locus. A unique VKORC1 haplotype carrying the promoter mutation associated with AVK sensitivity showed especially high frequencies in all the 17 HGDP-CEPH East Asian population samples. VKORC1 and 24 neighboring genes were found to lie in a 505 kb region of strong linkage disequilibrium in these populations. Patterns of allele frequency differentiation and haplotype structure suggest that this genomic region has been submitted to a near complete selective sweep in all East Asian populations and only in this geographic area. The most extreme scores of the different selection tests are found within a smaller 45 kb region that contains VKORC1 and three other genes (BCKDK, MYST1 (KAT8), and PRSS8) with different functions. Because of the strong linkage disequilibrium, it is not possible to determine if VKORC1 or one of the three other genes is the target of this strong positive selection that could explain present-day differences among human populations in AVK dose requirement. Our results show that the extended region surrounding a presumable single target of positive selection should be analyzed for genetic variation in a wide range of genetically diverse populations in order to account for other neighboring and confounding selective events and the hitchhiking effect.

Vitamin k intake and plasma desphospho-uncarboxylated matrix Gla-protein levels in kidney transplant recipients

Vitamin K is essential for activation of γ-carboxyglutamate (Gla)-proteins including the vascular calcification inhibitor matrix Gla-protein (MGP). Insufficient vitamin K intake leads to production of uncarboxylated, mostly inactive proteins and contributes to an increased cardiovascular risk. In kidney transplant recipients, cardiovascular risk is high but vitamin K intake and status have not been defined. We investigated dietary vitamin K intake, vascular vitamin K status and its determinants in kidney transplant recipients. We estimated vitamin K intake in a cohort of kidney transplant recipients (n = 60) with stable renal function (creatinine clearance 61 [42-77] (median [interquartile range]) ml/min), who were 75 [35-188] months after transplantation, using three-day food records and food frequency questionnaires. Vascular vitamin K status was assessed by measuring plasma desphospho-uncarboxylated MGP (dp-ucMGP). Total vitamin K intake was below the recommended level in 50% of patients. Lower vitamin K intake was associated with less consumption of green vegetables (33 vs 40 g/d, p = 0.06) and increased dp-ucMGP levels (621 vs 852 pmol/L, p<0.05). Accordingly, dp-ucMGP levels were elevated (>500 pmol/L) in 80% of patients. Multivariate regression identified creatinine clearance, coumarin use, body mass index, high sensitivity-CRP and sodium excretion as independent determinants of dp-ucMGP levels. In a considerable part of the kidney transplant population, vitamin K intake is too low for maximal carboxylation of vascular MGP. The high dp-ucMGP levels may result in an increased risk for arterial calcification. Whether increasing vitamin K intake may have health benefits for kidney transplant recipients should be addressed by future studies.