What are blood platelets and why is a normal platelet count important?

Written by: Top Doctors®
Edited by: Top Doctors®

Blood is crucial to the functioning of the human body. It is a liquid formed of three components: plasma, which carries a significant number of substances necessary for our life, and three types of cells: red blood cells, white blood cells, and platelets.

What are platelets?

Platelets are portions of a larger cell, called a megakaryocyte (a large bone marrow cell). Each megakaryocyte, upon fragmentation, produces hundreds of platelets that pass into the blood. These, having no nucleus, cannot be divided or reproduced. They usually last for about 9 days in the bloodstream. There are continually small breaks in blood vessels that are plugged by platelets. They have the ability to detect the ruptured or injured blood vessels and fix them, helping to stop the bleeding immediately. Subsequently, they help initiate blood clotting. According to haematologists, platelets are indispensable to ensure the integrity of the blood circulation and also play the crucial role of stopping bleeding. The normal platelet count is between 120,000 and 400,000 per microlitre of blood. Generally, it is necessary to investigate the platelet count when it is consistently less than 100,000 or greater than 500,000.

Problems associated with platelets

There are three types of problems associated with platelets:

Thrombocytopenia (fewer platelets than normal)

This is the most frequent problem, however, most of the time it does not have repercussions because, although there are fewer platelets, they are still able to ensure a correct haemostasis (normal blood circulation without bleeding). If the number of platelets is very low, the patient will have cardinal problems and haemorrhages.

Thrombocytosis (more platelets than normal)

An increased platelet count is a physiological defence mechanism in cases of inflammation and infection. If the platelet count is too high, there is an increased risk of thrombosis. The clearest example of this problem occurs in a blood disease called essential thrombocythemia, in which the patient may have two to five times more platelets than usual. Another frequent cause of high platelets is a low iron level, a situation that must always be monitored in these patients.

Thrombocytopathy (poorly functioning platelets)

Although the platelet count may be normal, there is a tendency for bleeding. Most of this platelet malfunction is due to drug delivery. Drugs may have been administered intentionally to improve circulation or prevent thrombosis or it might be an adverse drug effect.


By Topdoctors

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