What is the importance of platelets in blood?

“Platelets are the cells that circulate within our blood and bind together when they recognize damaged blood vessels,” says Marlene Williams, M.D., director of the Coronary Care Unit at Johns Hopkins Bayview Medical Center. “When you get a cut, for example, the platelets bind to the site of the damaged vessel, thereby causing a blood clot. There’s an evolutionary reason why they’re there. It’s to stop us from bleeding.”

What makes platelets change their shape?

Platelets, the smallest of our blood cells, can only be seen under a microscope. They’re literally shaped like small plates in their non-active form. A blood vessel will send out a signal when it becomes damaged. When platelets receive that signal, they’ll respond by traveling to the area and transforming into their “active” formation. To make contact with the broken blood vessel, platelets grow long tentacles and then resemble a spider or an octopus.

What is a healthy platelet count?

A normal platelet count ranges from 150,000 to 450,000 platelets per microliter of blood. Having more than 450,000 platelets is a condition called thrombocytosis; having less than 150,000 is known as thrombocytopenia. You get your platelet number from a routine blood test called a complete blood count (CBC).

What it means to have too many platelets

The medical term for having too many platelets is thrombocytosis, and there are two types:

• Primary or essential thrombocytosis – Abnormal cells in the bone marrow cause an increase in platelets, but the reason is unknown.
• Secondary thrombocytosis – The same condition as primary thrombocytosis, but may be caused by an ongoing condition or disease such as anemia, cancer, inflammation, or infection.

When there are symptoms, they include spontaneous blood clots in the arms and legs, which if untreated can lead to heart attack and stroke. In severe cases, the patient might have to undergo a procedure called a platelet pheresis. This lowers the platelet count by removing the blood, separating out the platelets, and returning the red blood cells back to the body.

With secondary thrombocytosis, the symptoms are usually related to the associated condition. For example, if you have an infection or anemia, you treat those conditions and the platelet count comes down.

What it means to have too few platelets

When you don’t have enough platelets, it’s called thrombocytopenia. Symptoms include easy bruising, and frequent bleeding from the gums, nose, or GI tract. Your platelet count drops when something is preventing your body from producing platelets. There are a wide range of causes, including:

• Medications
• An inherited condition
• Certain types of cancer, such as leukemia or lymphoma
• Chemotherapy treatment for cancer
• Kidney infection or dysfunction
• Too much alcohol

How platelets relate to cardiovascular disease

If you have too many platelets, it can increase your risk for clotting. But often your cardiovascular risk has more to do with platelet function than platelet number. For example, you could have a healthy number of platelets, but if they’re sticking together too much it can increase your chance of having a heart attack or stroke.

Keeping track of your platelets

Too many platelets, too few platelets, abnormally functioning platelets, and related conditions such as blood clots, strokes, and heart attacks can be inherited. So it’s a good idea to alert your doctor when there’s a family connection.

“Although you may feel fine, your physician might want to keep a close eye on you and investigate whether or not you need medications to reduce the functioning of your platelets,” says Williams. “The most common blood-thinning medication is aspirin, although recent studies have shown that women under 65 who are otherwise healthy do not receive the same benefit from aspirin as men do. There is no concrete answer to that yet.”

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Overview

What are platelets?

Platelets, also called thrombocytes, are tiny components of your blood that help with clotting. Platelets are your body’s natural bandage to stop bleeding.

Function

What do platelets do?

Your platelets function to stop bleeding. During an injury, your platelets will cluster together at the site of the wound to act as a plug, sealing blood vessels in a process called clotting to prevent excess blood from leaving your body.

Can I donate platelets?

Yes, you can donate your platelets in a process similar to donating blood plasma. To do so, your healthcare provider will draw blood from one arm and place it into a centrifuge machine, which quickly spins and separates the components of your blood. The machine removes platelets from your blood and the remaining blood components return to your body through a vein in your opposite arm. Platelet donations help individuals who have chronic illnesses, cancer or serious injuries.

Anatomy

Where are platelets located?

Platelets are components in your blood and spleen. Whole blood consists of plasma, red and white blood cells and platelets. Since platelets are the lightest component of whole blood, they are pushed to the walls of your blood vessels, allowing plasma and blood cells to flow through the center, which helps platelets reach injury quickly to prevent bleeding.

What do platelets look like?

Platelets are small, colorless fragments of cells. Platelets form in the shape of a plate, which is where they get their name. Proteins on the exterior of your platelet walls are sticky to help it adhere to your blood vessels. When actively clotting, platelets extend filaments that resemble legs on a spider. These legs make contact with the broken blood vessel and other clotting factors to seal the damage and stop the bleeding.

How many platelets are in my blood?

Platelets and white blood cells make up 1% of your whole blood along with plasma (55% total volume) and red blood cells (44% total volume). There is about one platelet for every 20 red blood cells in your body. In a single drop of blood, there are tens of thousands of platelets.

Where are platelets made?

Platelets form in the soft tissue of your bones (bone marrow). The largest cells in your bone marrow (megakaryocytes) make platelets.

Conditions and Disorders

What is a normal platelet count?

During a complete blood count test (CBC), your healthcare provider will remove a sample of your blood from your vein to test how many white blood cells, red blood cells and platelets are in the sample. A normal platelet count for adults ranges from 150,000 to 450,000 platelets per microliter of blood. Any count above 450,000 or below 150,000 would be risk factors for platelet-related conditions.

What are common conditions that affect platelets?

There are two conditions that are the result of an abnormal platelet count:

• Thrombocytopenia: Low platelet count can lead to bruising and excessive bleeding.
• Thrombocytosis: High platelet count can lead to abnormal blood clotting.

What causes my platelet count to be too high?

Abnormal cells in your bone marrow cause your platelet count to be too high. The reason for abnormal cell formation is unknown.

What causes my platelet counts to be too low?

Potential causes for low platelet count include:

• Alcohol use disorder.
• Viral (hepatitis C, HIV) or bacterial infections.
• Autoimmune diseases.
• Bone marrow diseases (anemia) or cancer.
• Enlarged spleen.
• Chemical exposure.
• Side effect of a medication or treatment.
• Kidney infections or dysfunction.

In most cases, managing pre-existing medical conditions can improve low platelet counts.

What happens if platelet counts are low?

If your platelet count is too low (thrombocytopenia), you won’t have enough platelets to clot a wound. In the event of an injury, you may bleed too much and it could be difficult to stop. Low platelet count can lead to excessive blood loss, hemorrhaging and internal bleeding, which could be life-threatening.

Severe cases of bleeding inside of your body and underneath your skin as a result of not having enough platelets is a bleeding disorder called immune thrombocytopenia (ITP). This condition causes tiny red and purple dots on your skin (petechiae) that resembles a rash along with bruises from blood vessels under your skin (purpura). Treatment to increase your platelet count improves your prognosis for ITP.

What happens if platelet counts are high?

If your platelet count is too high, platelets will stick together and cause unnecessary clotting in your blood vessels. Blood clots could lead to heart attack and stroke.

What are symptoms of platelet conditions?

Common symptoms of platelet conditions include:

• Bruising.
• Frequent nose bleeds or bleeding gums in your mouth.
• Blood in your stool or urine.
• Internal bleeding.
• Excessive bleeding from small wounds.
• Heavy menstrual periods.
• Muscle, joint pain, tingling in hands/feet, leg swelling.
• Severe headaches, dizziness or weakness.

What tests check the health of my platelets?

Tests that check the health of your platelets include:

• Complete blood count: A blood test identifies how many blood cells and platelets are circulating throughout your body. This test evaluates your overall health and can detect a number of diseases and conditions.
• Platelet count: Your healthcare provider will use a sample of your blood from a complete blood count test to identify how many platelets are in the sample.
• Bone marrow biopsy: Your healthcare provider removes a sample of your bone marrow to examine the health of your cells where platelets form.

Common treatments for platelet conditions include:

• Receiving blood transfusions.
• Taking steroids or antibiotics.
• Undergoing surgery to remove your spleen (splenectomy).
• Taking a low dose of aspirin regularly.

Care

How do I decrease my blood platelet count if it is too high?

If your blood platelet count is too high, your healthcare provider will recommend a treatment plan to address your health concern. Solutions to decrease your blood platelet count include:

• Taking a low dose of aspirin daily.
• Removing platelets from your blood (platelet pheresis).
• Treating any underlying medical conditions.

How do I increase my blood platelet count if it is too low?

There aren’t any specific lifestyle changes that will increase your blood platelet count. The best option is treating underlying medical conditions and working closely with your healthcare provider to find a treatment plan that works best with your body.

How do I keep my platelets healthy?

You can keep your blood platelets healthy by:

• Limiting your alcohol intake.
• Not smoking.
• Avoiding toxic chemicals.
• Being cautious and careful to avoid injury.

Frequently Asked Questions

What is platelet-rich plasma?

Platelet-rich plasma assists in healing and/or repairing injuries to your body, including sports injuries, joint sprains, pulled muscles, liver disease and large wounds. Platelet-rich plasma forms after a sample of your blood is withdrawn and placed into a centrifuge machine, which separates your whole blood into layers. Plasma and platelets separate from red and white blood cells, and your healthcare provider will inject the platelet-rich plasma to the site of your injury via a shot.

A note from Cleveland Clinic

Platelets are a vital portion of your blood that help you recover from injury quickly. Take steps to improve the health of your platelets by managing any pre-existing medical conditions and being cautious to avoid injury.

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