Platelets Blood Test

What are platelets?

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Platelets are the smallest of your blood cells that are circulating in the body along with red blood and white blood cells. In their inactive form, they resemble small plates, hence called platelets. The scientific name of platelets is thrombocytes. Platelets become activated when they receive a signal from an injured or damaged blood vessel. They travel to the area and contact the broken blood vessel. The shape of the platelets changes as they grow long extensions or tentacles similar to a spider or an octopus and lead to the formation of a blood clot or mesh of platelets and other substances. This helps in preventing bleeding.

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Why is a platelets blood test done?

A platelets blood test is generally done as part of a Complete Blood Cell Count with differential. Your doctor will recommend this test due to the following reasons:

• To review your overall health: As a component of a routine medical examination to monitor your general health and to screen for different disorders such as anemia or cancer
• To diagnose a medical condition: In case you have weakness, fatigue, fever, inflammation, bruising or bleeding
• To monitor a medical condition: In case you have been diagnosed with a bleeding disorder that affects platelet cell counts
• To monitor medical treatment: In case you are taking medications that may affect platelet cell counts

What conditions cause a change in the platelet levels?

Low platelet count

A low platelet count is referred to as thrombocytopenia. Thrombocytopenia can be inherited or acquired.

Inherited

Inherited means that a gene is passed through your parents. Inherited low platelet count occurs due to a defect in the bone marrow.  A defect appears in the production of platelets that affects both the number and the process of maturation of these cells.

Acquired

Acquired means that you develop a condition during your life rather than being born with it or inheriting it from your parents. The causes of acquired low platelet count include:

• Infections: Viruses such as mononucleosis, HIV, AIDS, measles, and hepatitis, bacterial infections, sepsis
• Medications: Medications such as aspirin, ibuprofen, quinidine, H2 blockers
• Liver conditions such as cirrhosis
• Chronic bleeding
• Cancer: Cancer that spreads to the bone marrow
• Autoimmune conditions: Autoimmune conditions such as lupus and Crohn’s disease
• Ageing: Platelet count tends to decrease with age
• Immune-mediated: Your immune system targets and destroys the platelets, which leads to a decrease in the number of platelets. This condition is called immune thrombocytopenia (ITP). Usually, your immune system defends your body against infections and diseases.

High platelet count

A high platelet count is referred to as thrombocythemia or thrombocytosis.

Thrombocythemia

Thrombocythemia is also referred to as primary or essential thrombocythemia. In this condition, a high platelet count is not caused by another health condition but occurs due to a defect in the bone marrow.  A defect appears in the production of platelets that affects the number and process of maturation of the platelets, leading to an increase in the number of platelets.

Thrombocytosis

Thrombocytosis is often referred to as secondary or reactive thrombocytosis. A high platelet count is often a symptom of another underlying disease in this condition. Some of the conditions that cause high platelet levels include:

• Anemia: Iron-deficiency anemia, hemolytic anemia, acute blood loss can high platelet levels
• Cancer: Cancers of lung, gut, breast, or ovaries cause a high platelet count. This can be a first sign of cancer
• Surgery to remove your spleen: Removing your spleen can lead to a high platelet count. The spleen is an organ in the left upper abdomen that stores platelets
• Inflammation or infections: Conditions that cause inflammation, such as arthritis,  inflammatory bowel disease, and infections such as tuberculosis, can raise your platelet count

Your platelet count may temporarily increase because of the following:

• Recovery from serious blood loss
• Recovery from a very low platelet count caused by drinking too much alcohol and having low levels of vitamin B12 or folate
• Acute infection or inflammation
• Recovering from a recent injury
• Intense physical activity or exertion, such as from running a marathon

What are the symptoms of low and high platelet counts?

Low platelet count

A mild decrease in platelet count does not cause symptoms. The main symptom of thrombocytopenia involves bleeding. 

 Bleeding can manifest in several ways including:

• Bleeding that lasts a long time, even from minor injuries
• Petechiae are tiny, flat red spots under the skin as a result of leakage from blood vessels
• Purpura is bleeding under your skin that can cause red, purple, or brownish-yellow spots
• Nosebleeds or bleeding from your gums
• Blood in your urine or stool, which might look bright red or have a dark, tarry colour
• Heavy menstrual bleeding

High platelet count

Many individuals with high platelet counts often do not experience any symptoms. The main symptoms of a high platelet count are associated with blood clots and bleeding. 

Blood clots

Blood clots most frequently form in the brain, hands, and feet; however, the clots can develop anywhere in the body. When they form in the brain, they may cause chronic headaches and dizziness, and in severe cases, can lead to a stroke. Your hands and feet may feel numb and red, with a burning sensation and throbbing pain. The other symptoms of a blood clot include confusion, seizures, discomfort in one or both arms, your back, neck, jaw, or abdomen, shortness of breath, chest pain, nausea, and complications in pregnancy.

Bleeding

Bleeding can occur as nosebleeds, bruising, bleeding from your mouth or gums, or blood in your stool. It occurs when your body’s platelets are used up to form a clot. In this situation,  there is an inadequate number of platelets left in your bloodstream to effectively seal off cuts or breaks on the blood vessel walls. Additionally, bleeding can occur if your platelets are not working correctly.

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How do you prepare for your platelets blood test?

No special preparations are required for a platelets blood test.

A platelets blood test is ordered as part of a complete blood count (CBC). You are not required to fast for this test; however, you may be required to fast for 8-12 hours, depending on other tests you may have scheduled. It is recommended to stay hydrated by consuming an adequate amount of water when fasting. Your doctor will let you know if you need to follow any special instructions.

The general steps of a blood test involve the following:

• A medical laboratory technician will check your arms for a vein that can be reached comfortably. This is usually in the inner part of your arm on the other side of your elbow
• Upon location of the vein, they would clean and disinfect the area
• They would then insert a small needle into your vein to draw a blood sample, which might feel like a slight pinch
• After they insert the needle, a small amount of blood will collect in a test tube
•  They will remove the needle and press the bleeding site with a cotton ball or gauze to stop the bleeding
• A bandage will be applied on the site and the collection of the sample will be done
• After a healthcare provider has collected your blood sample, they’ll send it to a laboratory for testing. Once the test results are back, your doctor will share the results with you

Interpretation of test results

The optimal reference range of platelet count for adults is 150-400x10⁹/L. 

The values lower than 150x10⁹/L are termed thrombocytopenia or low platelet count. Values higher than 400x10⁹/L are called thrombocythemia, thrombocytosis or high platelet count. Many factors determine the levels of platelets in your body. Your doctor will recommend additional testing based on your signs and symptoms.

What can you do if you have low or high platelet counts?

Low platelet count

Treatment for a low platelet count depends on the cause and your symptoms. 

• Exercise: Avoid strenuous exercise, contact sports, or other activities if you are at a risk of bleeding due to a low platelet count. Walking, stationary cycling, or strength training can be done. If your child has a low platelet count, consult with their doctor about physical activity.‍
• Mild: You may not need treatment for a mild decrease in platelet count. ‍
• Severe: You may require medicines such as corticosteroids or procedures such as a blood transfusion if you have severe bleeding.  Additionally, any underlying condition causing the low platelet count must be treated.‍
• Medications: Your doctor will stop medications such as ibuprofen, aspirin, and heparin as they decrease the platelet levels. Moreover, you will need another medicine to prevent blood clotting.‍
• Immune-mediated: If your immune system is causing the low platelet count, you may be prescribed medicines to suppress the immune system.

High platelet count

• Thrombocythemia: Treatment of thrombocythemia depends on the symptoms.  If you have no symptoms, then no treatment is needed. However, medication or procedures may be required in case of moderate to severe symptoms. Treatment does not cure your condition, but it can help prevent blood clots and serious complications.

• Thrombocytosis: Treatment for secondary thrombocytosis varies according to the underlying cause. You usually do not need platelet-lowering medicines or procedures.  Platelets are typically normal and do not cause serious blood clots or bleeding.

What can you do to prevent complications?

You can follow some steps to help prevent complications with bleeding and blood clotting: 

• Follow up with your doctor for ongoing medical care: You may need routine tests to monitor your platelet levels. You may also need ongoing treatment to keep your platelet count within the normal range.

• Take all medicines as prescribed: Inform your healthcare provider or dentist about all medications before undergoing any surgery or dental procedure. Medicines such as aspirin thin your blood and may increase the risk of bleeding during these procedures.

• Monitor symptoms of bleeding: You must monitor for any bleeding, as excessive bleeding can create an emergency situation.

• Make healthy lifestyle changes: Lifestyle changes include taking a balanced diet, reducing stress, quitting smoking and reducing alcohol consumption. A balanced diet and reduced stress can help reduce inflammation in the body. Smoking promotes the formation of clots while alcohol decreases the number of platelets in your body.

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Sources:

1. John Hopkins Medicine - Health ‍

‍https://www.hopkinsmedicine.org/health/conditions-and-diseases/what-are-platelets-and-why-are-they-important

2. National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Platelet Disorders: Diagnosis; [updated 2025 Feb 18]. Available from: https://www.nhlbi.nih.gov/health/platelet-disorders/diagnosis‍

3. National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Thrombocytopenia; [updated 2025 Feb 18]. Available from: https://www.nhlbi.nih.gov/health/thrombocytopenia#:~:text=Thrombocytopenia