Vitamin K Deficiency in the Setting of Blenderized Tube Feeding Regimen in a Teenager: A Case Report.

Vitamin K acts a cofactor for the gamma-carboxylation of several proteins in the coagulation cascade. The clinical spectrum of vitamin K deficiency (VKD) can be asymptomatic to a significant bleeding. VKD is classically seen in newborns. However, this can manifest later in patients with risks such as sub-optimal nutrition, fat malabsorption, medications including antibiotics. A 17-year-old male with spinal muscular atrophy (SMA) Type 1, tracheostomy with ventilator dependent, gastrostomy tube feeding was seen by the gastroenterologist following treatment for small intestinal bacterial overgrowth (SIBO). Investigations showed coagulopathy following which he was transferred to the Pediatric ICU. Labs revealed prothrombin time (PT) 114 s [Normal 9.4-12.5 s], INR (International normalized ratio) 12.6 [Normal < 1.1] and partial thromboplastin time (PTT) 90 s [Normal 25.1-36.5 s]. Mixing studies and coagulation assays were consistent with VKD (low Factor VII and Factor IX with normal Factor V). His home blenderized feeding regimen met the caloric requirement but not the adequate intake (AI) values for vitamin K and other minerals. He received intravenous vitamin K (phytonadione) for five consecutive days with resolution of the coagulopathy (PT 13.2 s, PTT 37.1 s, INR 1.2). The patient was discharged on enteral vitamin K and additional supplements following dietary review by a nutritionist. Clinicians should be cognizant of VKD in patients on blenderized tube feeds which may not meet the adequate intake (AI) goals. In patients who are not receiving nutritionally complete formulas or receiving inadequate volumes, it is important to monitor macro and micronutrients.

Neglected vitamin K deficiency causing coagulation dysfunction in an older patient with pneumonia: a case report.

BACKGROUND: The development of coagulation disorders can be dangerous and fatal in the older people, especially those with multiple medical conditions. Vitamin K-dependent coagulation disorders are easily overlooked when anticoagulant drugs are not used and the patient shows no signs of bleeding. CASE PRESENTATION: We report a case of a 71-year-old male suffering from pulmonary infection with severe coagulation disorder without bleeding symptoms. He also had a history of Parkinson's disease, Alzheimer's disease and cardiac insufficiency. Coagulation tests were normal at the time of admission, prothrombin time (PT) is 13.9 (normal, 9.5-13.1) seconds and the activated partial thromboplastin time (APTT) is 30.2 (normal, 25.1-36.5) seconds. But it turned severely abnormal after 20 days (PT: 136.1 s, APTT: 54.8 s). However, no anticoagulants such as warfarin was used and no bleeding symptoms were observed. Subsequent mixing studies with normal plasma showed a decrease in prothrombin times. Vitamin K deficiency was thought to be the cause of coagulation disorders considering long-term antibiotic therapy, especially cephalosporins, inadequate diet and abnormal liver function. After supplementation with 20 mg of vitamin K, coagulation dysfunction was rescued the next day and serious consequences were effectively prevented. CONCLUSIONS: Overall, timely vitamin K supplementation with antimicrobials that affect vitamin K metabolism requires clinician attention, especially in older patients who are multimorbid, frail or nutritionally compromised, and are admitted to hospital because of an infection that needs antimicrobial therapy are at risk of clotting disorders due to abnormal vitamin K metabolism secondary to altered gut flora, which can exacerbate existing nutritional deficiencies.

Vitamin K Supplementation in Chronic Kidney Disease Patients: Where is the Evidence?

Vascular calcification (VC) is highly prevalent in Chronic Kidney Disease (CKD) patients, progresses gradually with deterioration of kidney function and is a strong, independent predictor of cardiovascular (CV) mortality. Matrix Gla Protein (MGP), the most potent inhibitor of VC, requires vitamin K as a co-factor to become biologically active. Accumulating epidemiological data have associated vitamin K depletion with VC progression and CV outcomes. CKD patients are characterized by poor vitamin K status and at the same time, pronounced CV calcification. In early and advanced CKD, including end-stage kidney disease, exogenous supplementation of vitamin K (especially with menaquinone 7, its most bioavailable form) might decrease the inactive form of MGP (dephosphorylated, uncarboxylated MGP) and probably retard the progression or even reverse VC. Here, we focus and discuss the interventional human studies of vitamin K supplementation in CKD patients and suggest future directions in this area of interest.

Hematochezia Due to Panitumumab-induced Colitis with Vitamin K Deficiency.

Panitumumab, a fully human anti-epidermal growth factor receptor (EGFR) monoclonal antibody, has been shown to be useful in treating either advanced or recurrent KRAS/NRAS/BRAF wild-type colorectal cancer. We herein report the case of a 60-year-old man with short bowel syndrome who developed hematochezia due to panitumumab-induced colitis with vitamin K deficiency during third-line chemotherapy. The cause of vitamin K deficiency was the lack of intravenous vitamin K supplementation following a change from central venous nutrition to peripheral venous nutrition. We advise clinicians to carefully check for colitis and manage the infusions of chemotherapy patients with short bowel syndrome.

Combining phosphate binder therapy with vitamin K2 inhibits vascular calcification in an experimental animal model of kidney failure.

BACKGROUND: Hyperphosphataemia is strongly associated with cardiovascular disease and mortality. Recently, phosphate binders (PBs), which are used to bind intestinal phosphate, have been shown to bind vitamin K, thereby potentially aggravating vitamin K deficiency. This vitamin K binding by PBs may offset the beneficial effects of phosphate reduction in reducing vascular calcification (VC). Here we assessed whether combining PBs with vitamin K2 supplementation inhibits VC. METHODS: We performed 3/4 nephrectomy in rats, after which warfarin was given for 3 weeks to induce vitamin K deficiency. Next, animals were fed a high phosphate diet in the presence of low or high vitamin K2 and were randomized to either control or one of four different PBs for 8 weeks. The primary outcome was the amount of thoracic and abdominal aorta VC measured by high-resolution micro-computed tomography (µCT). Vitamin K status was measured by plasma MK7 levels and immunohistochemically analysed in vasculature using uncarboxylated matrix Gla protein (ucMGP) specific antibodies. RESULTS: The combination of a high vitamin K2 diet and PB treatment significantly reduced VC as measured by µCT for both the thoracic (P = 0.026) and abdominal aorta (P = 0.023), compared with MK7 or PB treatment alone. UcMGP stain was significantly more present in the low vitamin K2-treated groups in both the thoracic (P < 0.01) and abdominal aorta (P < 0.01) as compared with high vitamin K2-treated groups. Moreover, a high vitamin K diet and PBs led to reduced vascular oxidative stress. CONCLUSION: In an animal model of kidney failure with vitamin K deficiency, neither PB therapy nor vitamin K2 supplementation alone prevented VC. However, the combination of high vitamin K2 with PB treatment significantly attenuated VC.

Role of Vitamin K in CKD: Is Its Supplementation Advisable in CKD Patients?

BACKGROUND: Patients with CKD are at an increased risk of developing vascular calcification (VC) and bone complications which translate into a higher morbidity and mortality. The dephosphorylated and uncarboxylated matrix Gla protein (dp-ucMGP) is considered to be an indicator of vitamin K2 status and correlates with markers of VC. It is activated by γ-glutamyl carboxylase that converts inactive MGP into an active form, and vitamin K2 is a cofactor of this reaction. The active form of MGP is a known inhibitor of arterial wall calcification and plays an important role in bone turnover. Recent studies show poor vitamin K2 status in CKD patients. We aimed to review the literature for the association between vitamin K2 status and calcification and bone disease risk and the efficacy of vitamin K2 supplementation in CKD population. SUMMARY: Most CKD patients, including those on renal replacement therapy, have vitamin K2 deficiency. The dp-ucMGP level, a marker of vitamin K2 status, is decreased by vitamin K2 supplementation in CKD patients, but there is no unequivocal proof that it influences arterial calcification progression and bone complications. Key Messages: CKD population are at risk of vitamin K deficiency. Supplementation of vitamin K2 is safe and improves the serum markers of its deficiency. There is lack of strong evidence that vitamin K2 supplementation slows progression of calcification or reduces the frequency of bone complications. More prospective studies are needed.

Vitamin K and cardiovascular complications in chronic kidney disease patients.

Vitamin K, well known for its role in coagulation, encompasses 2 major subgroups: vitamin K1 is exclusively synthesized by plants, whereas vitamin K2 mostly originates from bacterial synthesis. Vitamin K serves as a cofactor for the enzyme γ-glutamyl carboxylase, which carboxylates and thereby activates various vitamin K-dependent proteins. Several vitamin K-dependent proteins are synthesized in bone, but the role of vitamin K for bone health in chronic kidney disease patients, in particular the prevention of osteoporosis, is still not firmly established. Herein, we focus on another prominent action of vitamin K, in particular vitamin K2 (namely, the activation of matrix γ-carboxyglutamic acid protein, the most potent inhibitor of cardiovascular calcifications). Multiple observational studies link relative vitamin K deficiency or low intake to cardiovascular calcification progress, morbidity, and mortality. Patients with advanced chronic kidney disease are particularly vitamin K deficient, in part because of dietary restrictions but possibly also due to impaired endogenous recycling of vitamin K. At the same time, this population is characterized by markedly accelerated cardiovascular calcifications and mortality. High-dose dietary supplementation with vitamin K2, in particular the most potent form, menaquinone 7, can potently reduce circulating levels of dephosphorylated uncarboxylated (i.e., inactive matrix γ-carboxyglutamic acid protein) in patients with end-stage kidney disease. However, despite this compelling data basis, several randomized controlled trials with high-dose menaquinone 7 supplements in patients with advanced chronic kidney disease have failed to confirm cardiovascular benefits. Herein, we discuss potential reasons and solutions for this.

Vitamin K and vascular calcification.

PURPOSE OF REVIEW: Vascular calcification is a common and important cardiovascular risk factor in patients with chronic kidney disease (CKD). Recent advances in the understanding of the biology of vascular calcification implicate vitamin K-dependent proteins as important regulators in this process. This review highlights recent key advances in vascular biology, epidemiology, and clinical trials in this rapidly evolving field. RECENT FINDINGS: Vitamin K deficiency is associated with increasing severity of vascular calcification among patients with CKD, but the relationship with cardiovascular disease and mortality is inconsistent. Vitamin K may reduce calcification propensity by improving the activity of vitamin K-dependent calcification inhibitors or by down-regulating components of the innate immune system to reduce inflammation. However, recent randomized controlled trials in patients with diabetes, CKD, renal transplant, and on hemodialysis have failed to demonstrate improvement in vascular calcification or stiffness after vitamin K treatment. SUMMARY: Current evidence does not support a clinically useful role for vitamin K supplementation to prevent or reverse vascular calcification in patients with CKD. Knowledge gaps remain, particularly whether higher doses of vitamin K, longer duration of supplementations, or use a vitamin K as a part of a package of measures to counteract vascular calcification might be effective.

Treatment to reduce vascular calcification in hemodialysis patients using vitamin K (Trevasc-HDK): A study protocol for a randomized controlled trial.

INTRODUCTION: End stage renal failure patients on hemodialysis have significant vascular calcification This is postulated to be related to sub-clinical vitamin K deficiency, which is prevalent in hemodialysis patients. Vitamin K deficiency result in the failure of the matrix GLA protein (MGP) to undergo carboxylation. MGP is a natural local inhibitor of vascular calcification and the lack of functional carboxylated MGP may contribute to increase vascular calcification. Vitamin K supplement should therefore correct this anomaly and decrease the rate or severity of vascular calcification in this population of patients on long-term maintenance hemodialysis. Our study seeks to evaluate the prevalence and the progression of vascular calcification in a cohort of maintenance hemodialysis patients. It will also evaluate the efficacy of vitamin K supplementation in reducing the progression of vascular calcification in this group of patients. METHODS: This will be a single-center randomized, prospective and open-label interventional clinical trial of end stage renal failure patients on hemodialysis. We aim to recruit 200 patients. Eligible patients will be randomized to either the standard care arm or active treatment arm. Active treatment arm patients will receive standard care plus supplementation with oral vitamin K2 isoform 360 mcg 3 times weekly for a total duration of 18 months. Primary outcome measured will be absolute difference in coronary artery calcification score at 18-month between control and intervention arms. Secondary outcomes will be to compare absolute difference in aortic valve calcification, percentage of patients with regression of coronary artery calcification of at least 10%, absolute difference in aortic and systemic arterial stiffness, mortality from any cause and major adverse cardiovascular over the same period. DISCUSSION: Evidence of successful regression or retardation of vascular calcification will support the conduct of larger and longer-term trials aimed at reducing cardiovascular disease mortality and major adverse cardiovascular events in this high-risk population using a safe and inexpensive strategy TRIAL REGISTRATION:: ClinicalTrials.gov NCT02870829. Registered on 17 August 2016 - Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT02870829National University Hospital's Institutional Review Board (2015/01000).

Vitamin K deficiency: an emerging player in the pathogenesis of vascular calcification and an iatrogenic consequence of therapies in advanced renal disease.

Vascular calcification is a known complication of chronic kidney disease (CKD). The prevalence of vascular calcification in patients with non-dialysis-dependent CKD stages 3-5 has been shown to be as high as 79% (20). Vascular calcification has been associated with increased risk for mortality, hospital admissions, and cardiovascular disease (6, 20, 50, 55). Alterations in mineral and bone metabolism play a pivotal role in the pathogenesis of vascular calcification in CKD. As CKD progresses, levels of fibroblast growth factor-23, parathyroid hormone, and serum phosphorus increase and levels of 1,25-(OH)2 vitamin D decrease. These imbalances have been linked to the development of vascular calcification. More recently, additional factors have been found to play a role in vascular calcification. Matrix G1a protein (MGP) in its carboxylated form (cMGP) is a potent inhibitor of vascular calcification. Importantly, carboxylation of MGP is dependent on the cofactor vitamin K. In patients with CKD, vitamin K deficiency is prevalent and is exacerbated by warfarin, which is frequently used for anticoagulation. Insufficient bioavailability of vitamin K reduces the amount of cMGP available, and, therefore, it may lead to increased risk of vascular calcification. In vitro studies have shown that in the setting of a high-phosphate environment and vitamin K antagonism, human aortic valve interstitial cells become calcified. In this article, we discuss the pathophysiological consequence of vitamin K deficiency in the setting of altered mineral and bone metabolism, its prevalence, and clinical implications in patients with CKD.

Nutritional Therapy with Vitamin K1 Is Effective in the Improvement of Vitamin K Status and Bone Turnover Markers in Patients with Severe Motor and Intellectual Disabilities.

We have previously reported that patients with severe motor and intellectual disabilities (SMID) have a high prevalence of vitamin K deficiency both in the liver and bone. Thus, vitamin K therapy for SMID patients should be considered. In the present study, we have studied the efficacy of nutritional therapy with vitamin K1 for improving their vitamin K status and bone metabolism markers in patients with SMID. During the 3-mo period, 19 patients under enteral feeding received vitamin K1 treatment, the dose of which was determined to meet each subject's energy requirement. Biomarkers of vitamin K insufficiency; protein induced by vitamin K absence or antagonist-II (PIVKA-II), undercarboxylated osteocalcin (ucOC), intact osteocalcin (intact OC) and bone turnover markers (tartrate-resistant acid phosphatase-5b: TRACP-5b and bone alkaline phosphatase: BAP) were measured at baseline and post treatment. The ucOC/OC ratio was calculated as a more sensitive index than ucOC for vitamin K status in the bone. After treatment, the median vitamin K intake increased from 66 to 183 µg/d, and serum levels of PIVKA-II and ucOC/OC ratio were significantly decreased. Decrements of serum ucOC level and ucOC/OC ratio were significantly associated with vitamin K intake, indicating that both markers well reflect the dose-dependent vitamin K effects. Serum levels of BAP and TRACP-5b were significantly increased after vitamin K1 therapy. Nutritional therapy with vitamin K1 effectively improved the markers for vitamin K status and bone turnover, and was considered to be a good candidate for treatment in SMID patients.

Vitamin K supplementation for cystic fibrosis.

BACKGROUND: Malabsorption and deficiency of fat-soluble vitamins K may occur in cystic fibrosis, a genetic disorder affecting multiple organs. Vitamin K is known to play an important role in both blood coagulation and bone formation, hence the role of supplementation of vitamin K in this category needs to be reviewed. This is an updated version of the review. OBJECTIVES: To assess the effects of vitamin K supplementation in people with cystic fibrosis and to investigate the hypotheses that vitamin K will decrease deficiency-related coagulopathy, increase bone mineral density, decrease risk of fractures and improve quality of life in people with CF. Also to determine the optimal dose and route of administration of vitamin K for people with CF (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: 12 August 2019. SELECTION CRITERIA: 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 patients with cystic fibrosis. DATA COLLECTION AND ANALYSIS: Two authors independently screened papers, extracted trial details and assessed their risk of bias. The quality of the evidence was assessed using the GRADE criteria. MAIN RESULTS: Three trials (total 70 participants, aged 8 to 46 years) assessed as having a moderate risk of bias were included. One trial compared vitamin K to placebo, a second to no supplementation and the third compared two doses of vitamin K. No trial in either comparison reported our primary outcomes of coagulation and quality of life or the secondary outcomes of nutritional parameters and adverse events. Vitamin K versus control Two trials compared vitamin K to control, but data were not available for analysis. One 12-month trial (n = 38) compared 10 mg vitamin K daily or placebo in a parallel design and one trial (n = 18) was of cross-over design with no washout period and compared 5 mg vitamin K/week for four-weeks to no supplementation for four-weeks. Only the 12-month trial reported on the primary outcome of bone formation; we are very uncertain whether vitamin K supplementation has any effect on bone mineral density at the femoral hip or lumbar spine (very low-quality evidence). Both trials reported an increase in serum vitamin K levels and a decrease in undercarboxylated osteocalcin levels. The cross-over trial also reported that levels of proteins induced by vitamin K absence (PIVKA) showed a decrease and a return to normal following supplementation, but due to the very low-quality evidence we are not certain that this is due to the intervention. High-dose versus low-dose vitamin K One parallel trial (n = 14) compared 1 mg vitamin K/day to 5 mg vitamin K/day for four weeks. The trial did report that there did not appear to be any difference in serum undercarboxylated osteocalcin or vitamin K levels (very low-quality evidence). While the trial reported that serum vitamin K levels improved with supplementation, there was no difference between the high-dose and low-dose groups. AUTHORS' CONCLUSIONS: There is very low-quality evidence of any effect of vitamin K in people with cystic fibrosis. While there is no evidence of harm, until better evidence is available the ongoing recommendations by national CF guidelines should be followed.

Vitamin K role in mineral and bone disorder of chronic kidney disease.

Vitamin K is a key cofactor for the activation of proteins involved in blood coagulation, apoptosis, bone mineralization regulation, and vessel health. Scientific evidence shows an important role of activated osteocalcin and matrix-Gla protein in bone and vessels, markedly affected along the course of chronic kidney disease (CKD). In fact, CKD corresponds to an unique condition of vitamin K deficiency caused by dietary restriction, intestinal dysfunction, and impaired vitamin K recycling. Clinical data suggest that vitamin K status can be modulated and this prompts us to speculate whether patients with CKD might benefit from vitamin K supplementation. However, as important as whether the improvement in vitamin K status would be able to result in better bone quality, less vascular calcification, and lower mortality rates, several issues need to be clarified. These include better standardized methods for measuring vitamin K levels, and definition of the optimal concentration range for supplementation in different subgroups. Here, we review the literature data concerning the impact of vitamin K deficiency and supplementation on CKD-associated mineral and bone disorders (CKD-MBD). We present and discuss the available evidence from basic science and clinical studies, and highlight perspectives for further research.

Vitamin K in Chronic Kidney Disease.

Vitamin K is a composite term referring to a group of fat-soluble vitamins that function as a cofactor for the enzyme γ-glutamyl carboxylase (GGCX), which activates a number of vitamin K-dependent proteins (VKDPs) involved in haemostasis and vascular and bone health. Accumulating evidence demonstrates that chronic kidney disease (CKD) patients suffer from subclinical vitamin K deficiency, suggesting that this represents a population at risk for the biological consequences of poor vitamin K status. This deficiency might be caused by exhaustion of vitamin K due to its high requirements by vitamin K-dependent proteins to inhibit calcification.

Emerging Role of Vitamins D and K in Modulating Uremic Vascular Calcification: The Aspect of Passive Calcification.

Vascular calcification is a critical complication in patients with chronic kidney disease (CKD) because it is predictive of cardiovascular events and mortality. In addition to the traditional mechanisms associated with endothelial dysfunction and the osteoblastic transformation of vascular smooth muscle cells (VSMCs), the regulation of calcification inhibitors, such as calciprotein particles (CPPs) and matrix vesicles plays a vital role in uremic vascular calcification in CKD patients because of the high prevalence of vitamin K deficiency. Vitamin K governs the gamma-carboxylation of matrix Gla protein (MGP) for inhibiting vascular calcification, and the vitamin D binding protein receptor is related to vitamin K gene expression. For patients with chronic kidney disease, adequate use of vitamin D supplements may play a role in vascular calcification through modulation of the calciprotein particles and matrix vesicles (MVs).

Vitamin K deficiency: a case report and review of current guidelines.

BACKGROUND: Vitamin K, a fat soluble vitamin, is a necessary cofactor for the activation of coagulation factors II, VII, IX, X, and protein C and S. In neonatal period, vitamin K deficiency may lead to Vitamin K Deficiency Bleeding (VKDB). CASE PRESENTATION: We present the case of a 2 months and 20 days Caucasian male, presented for bleeding from the injections sites of vaccines. At birth oral vitamin K prophylaxis was administered. Neonatal period was normal. He was exclusively breastfed and received a daily oral supplementation with 25 µg of vitamin K. A late onset vitamin K deficiency bleeding was suspected. Intravenous Vitamin K was administered with complete recovery. CONCLUSIONS: Nevertheless the oral prophylaxis, our case developed a VKDB: it is necessary to revise the current guidelines in order to standardize timing and dosage in different clinical conditions.

Coagulopathy in Zellweger spectrum disorders: a role for vitamin K.

INTRODUCTION: Zellweger spectrum disorders (ZSDs) are caused by an impairment of peroxisome biogenesis, resulting in multiple metabolic abnormalities. This leads to a range of symptoms, including hepatic dysfunction and coagulopathy. This study evaluated the incidence and severity of coagulopathy and the effect of vitamin K supplementation orally and IV in ZSD. METHODS: Data were retrospectively retrieved from the medical records of 30 ZSD patients to study coagulopathy and the effect of vitamin K orally on proteins induced by vitamin K absence (PIVKA-II) levels. Five patients from the cohort with a prolonged prothrombin time, low factor VII, and elevated PIVKA-II levels received 10 mg of vitamin K IV. Laboratory results, including thrombin generation, at baseline and 72 h after vitamin K administration were examined. RESULTS: In the retrospective cohort, four patients (13.3%) experienced intracranial bleedings and 14 (46.7%) reported minor bleeding. No thrombotic events occurred. PIVKA-II levels decreased 38% after start of vitamin K therapy orally. In the five patients with a coagulopathy, despite treatment with oral administration of vitamin K, vitamin K IV caused an additional decrease (23%) of PIVKA-II levels and increased thrombin generation. CONCLUSION: Bleeding complications frequently occur in ZSD patients due to liver disease and vitamin K deficiency. Vitamin K deficiency is partly corrected by vitamin K supplementation orally, and vitamin K administered IV additionally improves vitamin K status, as shown by further decrease of PIVKA-II and improved thrombin generation.

Vitamin K deficiency: the linking pin between COPD and cardiovascular diseases?

Cardiovascular diseases are prevalent in patients with chronic obstructive pulmonary disease (COPD). Their coexistence implies that many COPD patients require anticoagulation therapy. Although more and more replaced by direct oral anticoagulants, vitamin K antagonists (VKAs) are still widely used. VKAs induce profound deficiency of vitamin K, a key activator in the coagulation pathway. It is recognized however that vitamin K is also an essential cofactor in the activation of other extrahepatic proteins, such as matrix Gla protein (MGP), a potent inhibitor of arterial calcification. No or insufficient MGP activation by the use of VKAs is associated with a rapid progression of vascular calcification, which may enhance the risk for overt cardiovascular disease. Vitamin K consumption, on the other hand, seems to have a protective effect on the mineralization of arteries. Furthermore, vascular calcification mutually relates to elastin degradation, which is accelerated in patients with COPD associating with impaired survival. In this commentary, we hypothesize that vitamin K is a critical determinant to the rate of elastin degradation. We speculate on the potential link between poor vitamin K status and crucial mechanisms of COPD pathogenesis and raise concerns about the use of VKAs in patients with this disease. Future intervention studies are needed to explore if vitamin K supplementation is able to reduce elastin degradation and vascular calcification in COPD patients.

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. This is an updated version of the review. 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: 30 January 2017. 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.

Vitamin K2 supplementation and arterial stiffness among renal transplant recipients-a single-arm, single-center clinical trial.

Subclinical vitamin K deficiency is prevalent among renal transplant recipients and is associated with an increased risk of cardiovascular disease. However, the association between vitamin K supplementation and improvement of arterial stiffness has not been explored in the renal transplant population. The KING trial (vitamin K2 In reNal Graft) is a single-arm study that evaluated the association between the change in vitamin K status and indices of arterial stiffness following 8 weeks of menaquinone-7 (vitamin K2) supplementation (360 µg once daily) among renal transplant recipients (n = 60). Arterial stiffness was measured using carotid-femoral pulse wave velocity (cfPWV). Subclinical vitamin K deficiency was defined as plasma concentration of dephosphorylated-uncarboxylated matrix Gla protein (dp-ucMGP) >500 pmol/L.At baseline, 53.3% of the study subjects had subclinical vitamin K deficiency. Supplementation was associated with a 14.2% reduction in mean cfPWV at 8 weeks (cfPWV pre-vitamin K2 = 9.8 ± 2.2 m/s vs. cfPWV post-vitamin K2 = 8.4 ± 1.5 m/s; P < .001). Mean dp-ucMGP concentrations were also significantly reduced by 55.1% following menaquinone-7 supplementation with a reduction in the prevalence of subclinical deficiency by 40% (P = .001). When controlled for age, durations of hemodialysis and transplantation, and the change in 24-hour mean arterial pressure, the improvement in arterial stiffness was independently associated with the reduction in dp-ucMGP concentration (P = .014).Among renal transplant recipients with stable graft function, vitamin K2 supplementation was associated with improvement in subclinical vitamin K deficiency and arterial stiffness. (Clinicaltrials.gov: NCT02517580).