What Are Platelets?

The Facts

Microsopic view of a blood platelet among red blood cells
A blood platelet (here coloured white) among red blood cells. The structures sticking out from the cell surface means the platelet is activated, causing the blood to clot.

Composition and function of the blood

Blood is made in the bone marrow. It is composed of red blood cells, platelets, plasma and white blood cells, collectively referred to as blood components. Donations given at our regular blood donation sessions are referred to as "Whole Blood". Platelets are very small cells. They work with the clotting factors in plasma to form a mesh "plug" to stop or prevent bleeding. Plasma is the fluid part of the blood. It contains protein, salts, antibodies and clotting factors. White cells fight harmful bacteria and help prevent infection. Red cells carry oxygen from the lungs to the tissues.

Why are platelet donors needed?

Most platelet donations are given to patients who are unable to make enough platelets in their bone marrow. For example, patients with leukaemia or other cancers may have too few platelets as the result of their disease or treatment. Also after major surgery or extensive injury, patients may need platelet transfusions to replace those lost through bleeding. Platelets given by our generous and committed donors are often life-saving and special in that they can help up to 3 adults or even 12 children! What's more, as platelets can only be stored for a few days, regular donations are always in great demand. We appreciate donors giving as often as they are able to, all donations make such a difference to the patients receiving them.

What does platelet donation by machine involve?

When you arrive for your donation you will register at the reception desk and complete the health questionnaire as normal. Then you will be seen for a further health assessment. We will ask for your consent to contact your GP if more information is necessary. All information you give is confidential. If you are eligible, a full explanation of the procedure including possible side effects will be given. If you are happy to proceed then you will be asked to sign a consent to join the panel of platelet donors. If you are not suitable you should not be alarmed as about half of our whole blood donors are eligible for platelet donation.