10 Facts About Platelets

what are platelets
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Platelets Definition

To start off, what is platelets? Also called thrombocytes, platelets carry the function of stopping bleeding by performing clogging and clumping mechanisms at the site of impaired blood vessel following an injury.

If we have to define platelets the simplest way, it’s the blood component primarily important during the blood clotting process. Blood platelets control bleeding with the help of several coagulation factors in the blood system.

The blood component is actually fragments of cytoplasm produced in the bone marrow without cell nucleus. It is formed out of the fragmentation of megakaryocytes and later released into blood circulation.

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


What are platelets? Below are some interesting aspects about blood 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 to 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 coagulation. The process starts when a blood vessel is damaged.

In the occurrence of an injury, since platelets are the smallest and the lightest of the three primary components in the blood stream, they are easily pushed out of the center 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 when not needed.

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

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

Active platelets clump to the fibers. This clumping provides an initial seal that prevents bleeding, a condition that would have 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 a lack of adequate circulating platelets can be classified under increased consumption or destruction of existing platelets, or reduced production in the bone marrow.

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

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

Thrombocytopenia symptoms may 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 underlying medical condition, infection, or disease such as inflammation, infection, anemia or cancer.

Thrombocytosis symptoms include spontaneous clotting of blood in the arms and legs, which can lead to heart attack as well as stroke if left 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 drawing of blood is followed by a separation process of collecting the platelets out of the blood and eventually returning the remaining blood cells back into the body.

5. Platelets are related to cardiovascular diseases

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

However, cardiovascular risk is more associated to platelet function than platelet count. An individual may have a normal amount of platelets, but due to abnormal function where the blood component sticks together too much, the clumping increases the chance of heart attack or stroke.

6. Platelets can be transfused

In patients with a low platelet 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 platelet transfusions are rare since, the 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 blood component or attacks the source; which are megakaryocytes cells in the bone marrow that are the core resource in the manufacturing of platelets.

Other 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 it have been affected by any drug/s 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 that are known to affect platelet function, supplementary strategies to increase platelet production, and treatment of underlying conditions. Read about foods that increase 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 a greater volume of platelets. Some medical disorders that causes thrombocytopenia as a result of the 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 bone marrow affects the blood component, too.

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

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About the Author:

Melissa Gomez, RN, MSN is a board certified nurse and has been a contributing writer for the past five years. Ms. Gomez has a special focus on platelet-related illness prevention and health promotion.

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