Blocking the activity of vitamin K can harm the bones of children

October 22, 2008

Blocking vitamin K activity in the body via the use of the anticoagulant drug warfarin can have a detrimental effect on bone health in children, according to researchers.
They found children who took Coumadin anticoagulants long-term for preventing blood clots could inhibit vitamin K recycling, disturbing the equilibrium between bone formation and resorption. Thrombotic events are less frequent among children than adults, but the incidence is rising among children, said the researchers at Maastricht University in the Netherlands. “It seems that long-term use of coumarin derivatives (coagulants such as warfarin) may cause osteopenia in children with the risk of developing osteoporosis later in life,” they concluded.
The study compared 23 children taking coumarin type anticoagulants with a control group of 25. The study group were aged between 5 to 18 years and had all undergone therapy with 16 being given warfarin and seven a related drug - acenocoumarol. None had any history of bone disease. Bone mass density of the lumbar spine (L1-L4) was assessed using Dual Energy x-ray Absorptiometry (DEXA Scanning) and was expressed as Z score. A healthy z score is zero. The median z score of the study group was -1.065.
While none of the patients suffered from osteoporosis, 52% displayed signs of osteopenia. Two other studies with children had noted a reduction in bone mass density.
"This study provides an interesting insight into the effect of blocking vitamin K activity in the body, with potential long term ramifications for bone health," said Leon J Schurgers, senior scientist from VitaK, at Maastricht University.
Dr Schurgers added: "Previous research by our group and others looking at OAC therapy in patients showed a significant increase in arterial calcification. The inactivation of the vitamin K-dependent protein matrix Gla-protein leads to impaired protection against arterial calcification. However, also in the apparently healthy population, some 40 per cent impaired matrix Gla-protein is present."

     “This would explain [another] study, showing that high intake of vitamin K2 reduced cardiovascular disease by some 50 per cent. Clearly, given the role vitamin K plays in bone and cardiovascular health, we recommend increasing vitamin K intake from food and dietary supplements for all people. Individuals on OAC treatment should consult with their physician." The study is published in the August 2008 issue of the Journal of Pediatric Hematology/Oncology