Lack of iron linked to blood clots

A lack of iron may increase the risk of dangerous blood clots, according to UK research.

The findings suggest iron supplements might be a way to prevent deep vein thrombosis (DVT) and other types of potentially life-threatening clot.

Blood clots can cause lumps of blood can dislodge and travel to the lungs with fatal results, They can also cause painful swelling.

DVTs are often associated with long distance air travel and other situations that involve being immobile for extended periods of time.

British scientists looking for new blood clot risk factors studied 609 patients with haemorrhagic telangiectasia (HHT), an inherited disease of the blood vessels. Previous research had shown that HHT patients have a higher risk of blood clots, though the reasons were unclear.

Symptoms of HHT include excessive bleeding from the nose and gut, resulting in a loss of iron.

The study, published in the journal Thorax, showed that many of the patients had low iron levels because of iron loss through bleeding.

They also had a higher risk of blood clots, which disappeared when they took iron supplements.

A blood-iron level of six micromoles per litre compared with the normal mid-range figure of 17 micromoles led to a 2.5-fold increase in venous thrombosis risk.

"Our study shows that in people with HHT, low levels of iron in the blood is a potentially treatable risk factor for blood clots," said lead researcher Dr Claire Shovlin, from the National Heart and Lung Institute at Imperial College London.

"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."

Iron deficiency anaemia is thought to affect at least one billion people worldwide.

The association with clotting may have been missed before because blood iron levels fluctuate during the day. Also, other markers of iron deficiency can be spuriously high if certain medical conditions are present.

Consistent timing of blood samples was important to obtaining reliable data, said the scientists.

The link seems to be dependent on Factor VIII, a blood protein which promotes normal clotting.

Low iron levels were sternly associated with higher levels of Factor VIII, which in turn was a strong risk factor for clotting.

Making the blood clot more easily after losing iron might be an evolutionary trick to aid survival, said Dr Shovlin.

"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," she pointed out.