Platelet Count : test, high, low, causes and symptoms

Platelets, also called thrombocytes, are small cells found in the blood that play a key role in clotting and stopping bleeding. The platelet count refers to the number of platelets present in a given volume of blood. This article walks you through the importance of platelets, how they are measured, normal values, and the implications of abnormal levels.


Having too many or too few blood platelets or having platelets that do not work as they should can cause various conditions. The platelet count should be interpreted by a healthcare professional taking into account the clinical context.


◉ Definition and function of blood platelets

Platelets are small, colorless disc-shaped cells found in the blood and spleen. They are produced, along with white and red blood cells, in the bone marrow, more precisely from megakaryocytes. They can exist in two forms:

Blood platelets control bleeding in our body. If one of your blood vessels is damaged, it sends signals to platelets. The platelets then rush to the site of damage and form a plug (clot) to repair the damage.

◉ Normal and pathological levels of platelets count

The reference platelet count, usually expressed as the number of platelets per microliter (or mm3) of blood, may vary slightly between laboratories and specific populations.

Table 1 : Normal, low and high platelet count
Platelets per microliter (or mm3)
Normal platelet count 150,000 to 400,000
High platelet count Over 450,000

Low platelet count

low

Moderate

Serious

Severe

Less than 150,000

100,000 to 150,000

50,000 to 100,000

Less than 50,000

Less than 20,000

◉ Causes and Symptoms of Platelet Count Disorder

Low platelet count

A platelet count that is lower than normal is called thrombopenia or thrombocytopenia. This condition can cause:

Potential causes of a low platelet count include:

High platelet count

A platelet count that is higher than normal is called thrombocytosis or thrombocythemia. This can cause your blood to clot more than necessary and can cause:

Potential causes of a high platelet count include:

Note:

◉ Platelet count test

The platelet count test is a blood test commonly done to assess the number of platelets present in the blood. It is part of a complete blood count that measures different blood components, including red blood cells, white blood cells, and platelets.

Blood sample collection is usually performed by a lab technician using the following steps:

The collected blood sample is then analyzed using a small machine to count platelets (hematology analyzers) and other blood cells. This process usually takes a minute to generate the results.

◉ Additional tests

There are several additional tests that can be used to further assess platelet disorders:

◉ Conclusion

The platelet count is a common test performed to determine the amount of platelets in the blood. Platelets play a crucial role in blood clotting, helping to prevent excessive bleeding.

A decrease in the number of platelets can indicate the presence of specific infections or cancers. Conversely, a high platelet count can put you at risk for harmful blood clots and potential stroke. Therefore, the platelet count is considered an essential laboratory test investigation.


Référence

  1. NHLBI - Thrombocytopenia
  2. clevelandclinic - Platelet Count
  3. verywellhealth - Platelet Function Disorders Overview
  4. redcrossblood- Platelets and Thrombocytopenia
  5. visiblebody - No Nucleus? No Problem: Red Blood Cells and Platelets
  6. cancer.gov - platelet
  7. nhlbi - What Are Platelet Disorders?
  8. Marlene Stephanie Williams, M.D. - What Are Platelets and Why Are They Important?
  9. U-rochester - What Are Platelets?
  10. Pathologie des plaquettes