Donner Sang Compter

About platelets

Platelets are the smallest of the three major types of blood cells. They are only about 20% of the diameter of red cells. The normal platelet count is 150,000-400,000 per micro liter of blood but since platelets are so small, they make up just a tiny fraction of the blood volume. The principal function of platelets is to prevent bleeding.

Platelet Production
Platelets are produced in the bone marrow, the same as the red cells and most of the white blood cells. They are produced from very large cells called megakaryocytics. As megakaryocytics develop into giant cells, they undergo a process of fragmentation that results in the release of over 1,000 platelets per megakaryocytic. The dominant hormone controlling megakaryocytic development is thromboprotein (often abbreviated as TPO).

Platelet Structure
Platelets are actually not true cells but merely circulating fragments of cells. But even though platelets are cell fragments, they contain many structures that stop the bleeding. They contain proteins on their surface that allow them to stick to breaks in the blood vessel wall and also stick to each other. They contain granules that can secrete other proteins required for creating a firm plug to seal blood vessel breaks.

Platelet Function
Platelets are not only the smallest blood cell, they are the lightest. Therefore they are pushed out from the center of flowing blood to the wall of the blood vessel. There they roll along the surface of the vessel wall, which is lined by cells called endothelium. The endothelium is a very special surface, like Teflon, that prevents anything from sticking to it. However when there is an injury or cut, and the endothelial layer is broken, the tough fibers that surround a blood vessel are exposed to the liquid flowing blood. It is the platelets that react first to injury. The tough fibers surrounding the vessel wall like an envelope, attract platelets like a magnet, stimulate the shape change and platelets then clump onto these fibers, providing the initial seal to prevent bleeding, the leak of red blood cells and plasma through the vessel injury.

The process of platelets donation

Who can and who cannot give platelets?

Who can?

  • Age: 18 to 65 years old. Above that, it comes down to the overall health status.
  • Weight: on average >60Kg for men, >50Kg for women.
  • If you are feeling well, and display no signs of infection or bleeding.
  • You can give platelets almost every 10 to 14 days, up to 24 times a year.

Who can’t?

The same causes listed for blood donations apply here.

You can check them in this section under “Who can and who cannot give blood?”.

What happens when I give platelets? 

Before every platelets donation, you need to give a small sample of blood to determine if you have a high enough platelet count (>200,000).

During a platelet donation, a small portion of your blood is drawn from your arm and passed through a cell-separating machine. The machine collects the platelets and safely returns the remaining blood components, along with some saline, back to you.

The procedure, which takes around 90mins, is repeated between 5 and 7 times to collect in the end one platelet concentrate.