11:59am Sunday 17 December 2017

Low iron levels in blood give clue to blood clot risk

People with low levels of iron in the blood have a higher risk of dangerous blood clots, according to research published in the journal Thorax today. A study of clotting risk factors in patients with an inherited blood vessel disease suggests that treating iron deficiency might be important for preventing potentially lethal blood clots.

Each year, one in every 1,000 people in the UK is affected by deep vein thrombosis – blood clots that form in the veins. These can cause pain and swelling, but can also be fatal if the clot is dislodged and travels into the blood vessels of the lungs. Although some risk factors for blood clots are recognised, such as major surgery, immobility and cancer, often there is no clear reason for the blood clot.

To look for new risk factors for blood clots, scientists at Imperial College London studied patients with hereditary haemorrhagic telangiectasia (HHT). HHT is an inherited disease of the blood vessels, the main symptoms of which are excessive bleeding from the nose and gut. Previous research by the same group had found that HHT patients have a higher risk of blood clots, but the reason for this was unclear.

“Most of our patients who had blood clots did not have any of the known risk factors ,” said the paper’s lead author Dr Claire Shovlin, from the National Heart and Lung Institute at Imperial College London and an honorary consultant at Imperial College Healthcare NHS Trust. “We thought that studying people with HHT might tell us something important about the wider population.”

Dr Shovlin and her team analysed blood from 609 patients reviewed at the HHT clinic at Hammersmith Hospital from 1999 to 2011, to look for differences between the patients who had blood clots and those who did not. Many of the patients had low iron levels because of iron lost through bleeding. The researchers found that low levels of iron in the blood were a strong risk factor for blood clots. Patients who took iron supplements did not have higher risk, suggesting that treatment for iron deficiency can prevent blood clots.

“Our study shows that in people with HHT, low levels of iron in the blood is a potentially treatable risk factor for blood clots,” Dr Shovlin said. “There are small studies in the general population which would support these findings, but more studies are needed to confirm this. If the finding does apply to the general population, it would have important implications in almost every area of medicine.”

If the finding does apply to the general population, it would have important implications in almost every area of medicine.

– Dr Claire Shovlin

Iron deficiency anaemia is thought to affect at least 1 billion people worldwide. The association with blood clot risk might not have been found before because the iron levels demonstrating the link fluctuate during the day, and other markers of iron deficiency can be spuriously high if other medical conditions are present. Consistent timing of blood samples, as in this study, is therefore important for establishing correlations with health outcomes.

The link between iron levels and blood clots appears to be dependent on factor VIII – a blood protein which promotes normal clotting. High levels of factor VIII in the blood are also a strong risk factor for blood clots, and low iron levels were strongly associated with higher levels of factor VIII. The gene encoding factor VIII has sites where iron-binding proteins can bind, making it plausible that iron levels could regulate the factor VIII gene, and that this might be the mechanism for the link.

“We can speculate that in evolutionary terms, it might be advantageous to promote blood clotting when your blood is low in iron, in order to prevent further blood loss,” Dr Shovlin said.

The study was supported by the Imperial Comprehensive Biomedical Research Centre, established with a grant from the National Institute of Health Research.

For further information please contact:

Sam Wong
Research Media Officer
Imperial College London
Email: sam.wong@imperial.ac.uk
Tel: +44(0)20 7594 2198
Out of hours duty press officer: +44(0)7803 886 248

Notes to editors

1. Journal reference

J.A. Livesey et al. ‘Low serum iron levels are associated with elevated plasma levels of coagulation factor VIII and pulmonary emboli/deep venous thromboses in replicate cohorts of patients with hereditary haemorrhagic telangiectasia.Thorax, published online 15 December 2011. doi:10.1136/thoraxjnl-2011-201076

2. About Imperial College London

Consistently rated amongst the world’s best universities, Imperial College London is a science-based institution with a reputation for excelle nce in teaching and research that attracts 14,000 students and 6,000 staff of the highest international quality. Innovative research at the College explores the interface between science, medici ne, engineering and business, delivering practical solutions that improve quality of life and the environment – underpinned by a dynamic enterprise culture.

Sin ce its foundation in 1907, Imperial’s contributions to society have included the discovery of penicillin, the development of holography and the foundations of fibre optics. This commitment to the application of research for the benefit of all continues today, with current focus es including interdisciplinary collaborations to improve global health, tackle clima te change, develop sustainable sources of energy and address security challenges.

In 2007, Imperial College London and Imperial College Healthca re NHS Trust f ormed the UK’s first Academic Health Science Centre. This unique partnership aims to improve the quality of life of patients and populations by taking new discoveries and translating them in to new therapies as quickly as possible.

Website: www.imperial.ac.uk

3. About the NIHR

The National Institute for Health Research provides the framework through which the research staff and research infrastructure of th e NHS in England is positioned, maintained and managed as a national research facility. The NIHR provides the NHS with the support and infrastructure it needs to conduct first-class research funded by the Government and its partners alongside high quality patient care, education and training. Its aim is to support outstanding individuals (both leaders and collaborators), working in world-class facilities (both NHS and university), conducting leading edge research focused on the needs of patients. www.nihr.ac.uk

4. About NIHR Biomedical Research Centres

NIHR Biomedical Research Centres support research across a wide range of disease areas. These Centres are the most outstanding NHS/University research partnerships in the country; leaders in scientific translation and early adopters of new insights in technologies, techniques and treatments for improving health. To ensure they are able to succeed, the NIHR BRCs receive substantial levels of sustained funding. NIHR BRC funding supports the NHS infrastructure to create an environment where scientific endeavour can thrive, attracting the foremost talent and producing world-class outputs.


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