View this article online at http://patient.info/doctor/vitamin-k-deficiencyVitamin K DeficiencyProfessional Reference articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets. Vitamin K is found in green leafy vegetables and oils, such as olive, cotton seed, and soya bean. Other foods rich in vitamin K are green peas and beans, watercress, asparagus, spinach, broccoli, oats and whole wheat. Vitamin K is also synthesised by colonic bacteria.Vitamin K is an essential lipid-soluble vitamin. It is a co-factor in the synthesis of clotting factors II, VII, IX and X.[2]Vitamin K is also very important for bone health. Vitamin K deficiency is thought to cause impaired activation of bone matrix protein osteocalcin, and reduction of osteoblast function, resulting in impaired bone formation.[3] However, the clinical significance of this has not yet been fully evaluated.
There is growing evidence for a role of vitamin K in vascular health.Deficiency can occur in persons of any age but neonates are at risk of developing vitamin K deficiency bleeding (see the separate article on Vitamin K Deficiency Bleeding). This is because of a lack of vitamin K reaching the fetus across the placenta, the low level of vitamin K in breast milk and low colonic bacterial synthesis.Vitamin K deficiency is uncommon in otherwise healthy adults.Risk factorsExcessive anticoagulation with coumarins - eg, warfarin.Liver disease: for example, cirrhosis, malignancy, amyloidosis and Gaucher's disease decrease the synthesis of vitamin K-dependent factors.Malabsorption: coeliac disease, tropical sprue, Crohn's disease, ulcerative colitis, ascariasis, short bowel syndrome due to multiple abdominal surgeries, bacterial overgrowth, and chronic pancreatitis.Biliary tract disease: common duct obstruction due to stones and strictures, primary biliary cirrhosis, cholangiocarcinoma, and chronic cholestasis.
Leads to a decrease in fat absorption and so a deficiency of fat-soluble vitamins.Dietary deficiency occurs in people with malnutrition, including people with alcoholism, as well as patients undergoing long-term parenteral nutrition without vitamin K supplements.Drugs: colestyramine, salicylates, rifampin, isoniazid and barbiturates are some of the common drugs that are associated with vitamin K deficiency.Diseases with endogenously produced coagulation inhibitors (eg, lupus anticoagulant and antithrombins) and paraproteinaemias such as myeloma, may cause vitamin K deficiency.Miscellaneous causes include massive transfusion, disseminated intravascular coagulation, polycythaemia vera, nephrotic syndrome, cystic fibrosis, and leukaemia.See the separate separate article on Vitamin K Deficiency Bleeding for presentation in infants.The clinical manifestations in adults are evident only if hypoprothrombinaemia is present:Bleeding is the major symptom, especially in response to minor or trivial trauma.
Any site can be involved, including mucosal and subcutaneous bleeding, such as epistaxis, petechiae, haematoma, gastrointestinal bleeding, menorrhagia, haematuria and bleeding from gums.Vitamin K deficiency needs to be considered as a possible cause of any bleeding disorder.The differential diagnosis therefore includes leukaemia, disseminated intravascular coagulation, dysfibrinogenaemia, idiopathic thrombocytopenic purpura, scurvy, thrombotic thrombocytopenic purpura and von Willebrand's disease.Bleeding time, prothrombin time and activated partial thromboplastin time are all elevated.The most sensitive marker is the antibody test for high level of des-gamma-carboxy prothrombin (DCP) protein in vitamin K absence (PIVKA).The plasma level of vitamin K can be measured.Therapy depends on the severity of the bleeding and the underlying cause.In life-threatening bleeds, fresh frozen plasma (FFP) should be administered prior to vitamin K.Vitamin K is available as phytomenadione (vitamin K) and as the synthetic water-soluble analogue menadiol sodium diphosphate.
Intravenous (IV) injections should be given slowly, as fast IV injection can cause bronchospasm and peripheral vascular collapse.Intramuscular injections may lead to severe haematoma formation at the injection site if clotting is impaired.InfantsSee the separate article on Vitamin K Deficiency Bleeding.Haemorrhage in people taking warfarinSee the separate article on Oral Anticoagulants.Patients have a very good prognosis if the vitamin K deficiency is recognised early and treated appropriately.Morbidity correlates with severity of vitamin K deficiency, but severe bleeding can be fatal.A diet rich in vitamin K - eg, green leafy vegetables and oils (such as olive, cotton seed, and soya beans), green peas and beans, watercress, asparagus, spinach, broccoli, oats and whole wheat.Vitamin K given to neonates is very effective in preventing vitamin K deficiency bleeding.Menadiol sodium phosphate is a water-soluble synthetic vitamin K derivative that can be given orally to prevent vitamin K deficiency in malabsorption syndromes.
There's been a wave of supplements launched containing Vitamin K, particularly K2. Why do people take them? Not everybody will have heard of Vitamin K2. But more and more of us are consuming it in supplements, according to market research firm Mintel.It says new food, drink, vitamin and supplement product launches containing Vitamin K2 have gone up 183% globally between 2008 and 2012.The better known form of Vitamin K, Vitamin K1, posted a healthy, but slower growth - 96% - over the same reviewed period. The number of products containing Vitamin K1 still far outstrips those containing Vitamin K2. All types of Vitamin K were in 1% of all food, drink, vitamins and supplement launches last year, according to Mintel. But what is Vitamin K, what's the difference between K1 and K2, and why are people taking Vitamin K supplements?The NHS says Vitamin K has several important functions, for example blood clotting, which helps wounds heal properly. Babies are born with lower levels of Vitamin K, and for this reason the NHS offers an injection of it soon after birth to prevent internal bleeding problems.
There is also increasing evidence fat-soluble Vitamin K is needed to help build strong bones. Adults need approximately 0.001mg a day of Vitamin K for each kilogram of their body weight, according to the NHS. It says people should be able to get all they need by eating a varied and balanced diet, with any not needed immediately stored in the liver for future use.It cites green leafy vegetables such as broccoli and spinach, vegetable oils and cereals as good sources of Vitamin K. Small amounts can also be found in meat such as chicken and dairy foods.The NHS also advises that taking too many Vitamin K supplements might be harmful.Those taking anticoagulants should also take heed of the experience of an Ayrshire man with a mechanical heart, who was hospitalised after his eating too many Brussels sprouts - which contain lots of Vitamin K - counteracted their effect.So why are Vitamin K, and particularly Vitamin K2, supplements on the rise? Laura Jones, a global food science analyst at Mintel, says recent research has revealed Vitamin K2 has much broader health benefits than previously thought, and is increasingly being seen as a bone health ingredient."
Vitamin K1 has a relatively short half-life and is rapidly cleared from the blood and is cleared by the liver within eight hours. In comparison vitamin K2 has a longer half-life of up to 72 hours, meaning it remains biologically active in the body for longer. "Vitamin K2 is also absorbed better by the body, and is linked to cardiovascular health. It directs calcium to the bones, and prevents it from being deposited where it shouldn't be, for example arteries and organs, where it can cause harm," she says. The health claims for Vitamin K have had support from the European Food Safety Authority in recent years, with the body stating that "Vitamin K contributes to maintenance of normal bone," and "Vitamin K contributes to normal blood coagulation". The ageing population - especially in major markets like Europe, Japan, China and the US - is also having an impact on supplement sales, with an increase in osteoporosis resulting in more interest in bone health.The number of new products with bone health claims having grown 44% since 2009, according to Mintel.
And while calcium and Vitamin D continue to be the most common vitamins in food and supplements making a bone health claim, Jones thinks that as consumers' awareness of Vitamin K2 increases, so will its prevalence. But not everyone is convinced. Dr Sarah Jarvis, a general practitioner and regular guest on the BBC's The One Show, says there is no evidence to suggest that people aren't getting enough Vitamin K."I can see no reason why normal healthy people would need a Vitamin K supplement or any supplement - with the exception perhaps of Vitamin D - it's far better to have a balanced healthy diet," she says.She thinks supplements send the wrong message. "My feeling from young people that come into my clinic is that they think they can have a rubbish diet and take multi-vitamins to make up for it, which they can't. "And if older people are worried about their bones, it's more important they look at calcium and Vitamin D. Vitamin K is connected with clotting - too much can have a negative impact if, for instance, you're taking medicine like warfarin," she says.