What to Know About Platelet Count

Medically Reviewed by Nayana Ambardekar, MD on March 10, 2024
3 min read

Platelets are the smallest blood cells. They are shaped like literal plates when non-active. Platelets respond to the body’s signal that any part of the body is harmed and help create blood clots to stop bleeding. However, having too many or too few platelets in your blood can cause severe issues. A platelet count (called Mean Platelet Volume) shows the mean size of platelets you have in your blood.

A healthy platelet count is between 150,000 to 450,000 platelets per microliter of blood. If your platelet count is within that range, that may show that you have an average amount of platelets. However, if it falls under 150,000 or above 450,000, that could suggest that you have a health problem. Thrombocytopenia and thrombocytosis are two possible conditions that a low or high platelet count could be a sign of. 


If your platelet test shows that you have a platelet count of under 150,000 per microliter of blood, that means you have thrombocytopenia. Thrombocytopenia means that your body has trouble making enough blood clots to help you guard against injury or impact. People with thrombocytopenia find themselves bruising or bleeding quite easily. 

It is usually caused by:

  • Medications
  • Genetic conditions
  • Autoimmune disease
  • Cirrhosis, when scar tissue builds up on your liver.
  • Sepsis, a serious response from your body to an infection that can cause organ failure.
  • Cancers related to the blood or bone marrow
  • Chemotherapy treatment
  • Any issue related to the kidneys
  • Alcohol abuse
  • General problems with the bone marrow


Thrombocytosis is when the mean number of your platelets within your blood is higher than average. There are two types of thrombocytosis: primary and secondary.

Primary thrombocytosis is when abnormal cells get into bone marrow and increase the production of platelets. This condition is relatively mysterious, and its causes are not known. 

Secondary thrombocytosis is medically the same as primary thrombocytosis but is caused by some other condition or disease. It can be caused by cancer, inflammation, infection, bone marrow disease, or anemia (a deficiency of red blood cells). Typically, secondary thrombocytosis is treated by treating whatever is causing it.

Thrombocytosis can be very dangerous and lead to blood clotting at any moment in the limbs. These blood clots can lead to heart attacks and stroke. In its most severe form, it is treated by something called plateletpheresis. This is a procedure in which the platelets are artificially separated from the blood to regulate the mean number of platelets. 

When should I get a platelet count?

Usually, your doctor or healthcare provider will know when you need a platelet count. Your count will be a part of a broader test that will give you a lot of information on the makeup of your blood. This test is called a complete blood count or CBC and is a fairly routine exam. 

However, there are some occasions where you may be showing specific symptoms that require more immediate testing. Some of these symptoms that will prompt your doctor into giving you a CBC and platelet count are: 

  • Uncontrolled bleeding from minor cuts 
  • Regular nose bleeds
  • Red or purple spots on the skin
  • Easy bruising 

How should I prepare for a platelet count?

There are no special requirements that you need to prepare for when you get a platelet count done. However, your healthcare provider might be doing more than just a platelet count on your blood. In that case, you may have to fast or limit your water intake. Either way, they will let you know. 

What should I expect for the actual test?

Platelet counts are relatively non-invasive and quick. Your provider will take a small blood sample from one of your veins and then put the sample in a tube or vial. This usually takes around five minutes. 

There is very little that can go wrong in this test — and at most, you might feel some pain and have minor bruising from where your provider collects a blood sample. 

What factors could contribute to a misreading of my platelet count?

Occasionally, you could get a false result from the platelet count if your platelets stick together. This sticking together causes the machine that reads your blood to read your blood as having fewer platelets than it actually does. 

Other factors to think about around your test could be:

  • Altitude levels
  • Physical activity
  • Certain medications 
  • Menstrual cycle