How does zinc deficiency cause bleeding?

Is Zinc critical for the control of platelet cyclic nucleotide signalling? (Mr. Charlie Coupland) 

Hull researchers are uncovering the role of zinc in platelets and bleeding. Zinc plays an important role in the body. Zinc deficiency exists in many health problems, and is linked to excess bleeding. It is not yet known exactly how a lack of zinc causes bleeding. These researchers aim to find out, to help prevent blood loss in those at risk. Platelets are a key blood cell in stopping bleeding. Platelets are normally held in an inactive state due to the presence of two substances in the blood, prostacyclin and nitric oxide. After a cut, platelets are exposed to substances that cause them to overcome this block, become sticky and form a clot, which plugs the cut and stops the bleeding. A delicate balance must be maintained, as too much stickiness could cause a blood clot in an important artery – for instance causing a heart attack or stroke. If on the other hand platelets do not activate properly they fail to prevent excessive bleeding. The researchers believe that zinc is required for platelets to override the inactive state normally produced by prostacyclin and nitric oxide. Understanding how zinc is used by the platelet will help to identify the key pathways by which platelets respond to their environment and therefore help to prevent excessive blood loss. This is important for those with conditions where zinc is deficient, including obesity and cancer.