10 Things on What are Platelets

what are platelets

Introduction: Platelets Definition

To start off, what is platelets? To define platelets the most simple way, it is a blood component essential in blood clotting.

It carries the function of controlling bleeding by clogging and clumping at the site of any impaired blood vessel in times of injury. They are also called thrombocytes.

The cells perform a clotting process with the help of other coagulation factors in the blood system.

Platelets are fragments of cytoplasm that comes without cell nucleus. They are formed from the fragmentation of megakaryocytes in the bone marrow and later released into blood circulation.

Inactive platelets are normally biconvex-discoid in shape. The shape changes when becomes activated as a result of normal response to damage of a blood vessel. These non-nucleated platelets are only found in mammals.


The following are some few significant aspects to know on what are platelets

1. Platelets are formed in the bone marrow

Platelets, just like the red and the white blood cells, are produced in the bone marrow. As mentioned previously, they are basically formed out of large bone marrow cells known as megakaryocytes.

When these large cells – megakaryocytes – develop into giant cells, they usually undergo a complex process of fragmentation, resulting in the release of more than 1,000 platelets per single megakaryocyte.

Thrombopoietin is the dominant hormone that is responsible for the development of megakaryocytes and its fragmentation into platelets.

2. Mechanism of blood clotting by platelets

Platelets perform a significant task in blood clotting. The process happens when the blood vessel has been damaged.

In the occurrence of an injury, since platelets are the smallest cells and the lightest of all components in the blood stream, they are easily pushed out of the centre of flowing blood to the wall of the blood vessel.

However, the blood vessel wall in which they freely roll is lined by endothelium cells that prevent the platelets from sticking to it.

An injury or cut to the blood vessel breaks the endothelial layer, exposing the tough fibres surrounding the blood vessels that normally encloses the blood flow.

The tough fibres attract platelets, stimulating the change in shape from biconcave inactive platelets to the octopus like structure.

Active platelets then clump to the fibres. This clumping provides the initial seal that prevents bleeding, an instance that would otherwise lead to loss of red blood cells, white blood cells and plasma.

3. Platelets deficiency leads to thrombocytopenia

In a normal mammal, the number of platelet is measured to what is called as the platelet count. It normally ranges from 150,000 to 450,000 platelets per microliter of blood.

Having less than 150,000 platelet count per microliter of blood is known as thrombocytopenia. Reasons for lack of adequate platelets can be classified into increased consumption or destruction of the existing platelets, or reduced production of the platelets.

The lack of enough platelets – thrombocytopenia, can either be inherited or acquired by an individual. The blood disorder can lead to death because of much bleeding knowing that platelets have a crucial role in blood clotting – a function that has been impaired. Besides the dangers it can result to, the situation can also be deadly even in adults.

Other than hereditary factors, thrombocytopenia can also be caused by certain medications, certain types of cancer (such as leukaemia or lymphoma), chemotherapy treatment for cancer, kidney infection or dysfunction, much alcohol intake and bone marrow dysfunction or infection.

Thrombocytopenia symptoms include frequent bleeding from the gums, the nose, the GI tract and easy bruising.

4. Too many platelets lead to thrombocytosis

Thrombocytosis is a term used to describe the existence of too many platelets in the blood system. Thrombocytosis can be classified into two classes; Primary and secondary thrombocytosis.

Primary or essential thrombocytosis results from abnormal cells in the bone marrow, causing an increase in the number of platelets; due to a reason that is purely unknown.

Secondary thrombocytosis is due to increased platelet production in the bone marrow, caused by a known ongoing medical condition, infection or a disease such as inflammation, infection, anaemia or cancer.

Thrombocytosis symptoms include spontaneous clotting of blood in the arms and legs, which could lead to heart attack as well as stroke if untreated.

The patient, in severe cases might have to undergo platelet pheresis, a procedure that is meant to lower the platelet count by blood removal processes. The removal of blood is followed by a separation process of taking the platelets out of the blood and then eventually returning the remaining cells back into the body.

5. Platelets are related to cardiovascular diseases

Too many platelets increase the risk of blood clotting. Having blood clots in the blood vessels increase the chances for cardiovascular diseases to manifest.

Cardiovascular risk however, is more related to platelet function than platelet number. An individual could have a normal number of platelets, but due to abnormal function where they stick together too much, the clumping increases the chance of heart attack or stroke.

6. Platelets can be transfused

In cases of low platelets count or thrombocytopenia, doctors may recommend a platelet transfusion.

If the patient consents, platelets are collected from donors and run through a drip into the bloodstream of the patient.

The process of transfusion takes 15-30 minutes. Side effects in such transfusions are rare since, all donated platelets are thoroughly tested for infections.

7. Some drugs affect the functionality and the number of platelets

There are some medicinal drugs that are toxic to platelets which either directly kills the cells or attacks the source; which are megakaryocytes cells in the bone marrow that are core resource in the manufacture of platelets.

These drugs include those used in chemotherapy during cancer treatment. Mean Platelet Volume (MPV) will help determine the volume of platelets in a given blood and whether these body cells have been affected by any drugs introduced to the body.

8. Platelet transfusion has alternatives

The transfusion of platelet cells can only be set by medical doctors whether if it is the ideal solution to the platelet problem.

There are long-term alternatives to the need for transfusion which includes the discontinuation of drugs which are known to affect platelet function, supplementary strategies to increase platelet production, and treatment of underlying conditions. Read about foods to increase a low platelet count.

9. Splenic sequestration leads to reduced number of platelets

Splenic sequestration leads to low platelet count due to enlargement and changes in the function of the spleen for various reasons.

A large spleen retains more volume of platelets. Some medical disorders that causes thrombocytopenia as a result of this condition include advanced liver diseases with portal hypertension and blood cancers.

10. Cancer of the bone marrow affects platelets

Due to the fact that platelets are produced in the bone marrow, any infection or disease that affects the region affects them too.

Cancers of the bone marrow and that of the blood can result to various levels of thrombocytopenia. Cancers located on other body tissues may also infiltrate the functionality of the bone marrow, resulting in reduced production of blood platelets.


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