Platelets are small types of blood cells that prevent excessive bleeding. It’s possible to develop low or high platelet counts related to a number of health conditions.

Platelets are one of the main types of blood cells in your body, along with red blood cells and white blood cells. Also known as thrombocytes, platelets are responsible for helping your blood clot to prevent excess bleeding and to promote wound-healing.

Having a normal number of platelets in your bloodstream is important for these cells to perform their functions. However, problems can arise when your body makes too few or too many platelets. In other cases, your platelets don’t function at all like they should.

Learn more about blood platelets, including how they work in your body, as well as related health conditions and possible symptoms to discuss with a doctor.

Platelets help to form plugs called blood clots. This is important to slow down or prevent excess bleeding in the case of external or internal wounds. Without platelets, it’s possible to experience internal or spontaneous bleeding, which can be fatal.

When you get injured, platelets adhere to your blood vessel walls to help prevent further bleeding from occurring.

Platelets are made in your bone marrow. These are the smallest types of blood cells, with each one living approximately 7 to 10 days. Unlike red and white blood cells, platelets do not contain nuclei.

During the early stages of their formation, they are megakaryocytes, or large bone marrow cells. Each megakaryocyte contains an organelle that eventually becomes a smaller disc-sized platelet that can move easily through your bloodstream to help form clots and heal wounds.

Any platelet that is larger than its typical post-megakaryocyte size of 2 μm (microns) in diameter could indicate an underlying condition, such as a genetic disorder or an autoimmune disease.

Your spleen also plays a role in filtering and storing platelets.

A normal platelet count is considered anywhere between 150,000 and 400,000 platelets per microliter.

Any result above 450,000 platelets per microliter is considered high, while any level below 150,000 is considered a low platelet count.

A health care professional can make this determination based on blood test results. Depending on their findings, they may then order additional labs and tests, including a possible abdominal ultrasound.

A low platelet count (thrombocytopenia) and a high platelet count (thrombocythemia or thrombocytosis) can both be serious, and possibly fatal when left untreated. Each one can be associated with certain medical conditions.

Medical conditions that affect a low platelet count

Thrombocytopenia can prevent your blood from clotting like it is supposed to, and may lead to excess bleeding. The most common causes include:

  • Primary immune thrombocytopenia (ITP): Also called idiopathic ITP, this is a type of autoimmune condition in which your immune system attacks healthy platelets and destroys them. It may be treated with immunosuppressants or other medications.
  • Secondary ITP: This refers to low platelets caused by an existing autoimmune disease, such as rheumatoid arthritis (RA) and lupus.
  • Medications: These include acetaminophen (Tylenol), ibuprofen (Advil), and heparin. A doctor may have you discontinue the medication they suspect is causing low platelets.
  • Infections: Malaria, viral infections like hepatitis C and HIV, and sepsis may all decrease blood platelet levels.
  • Genetics: Some forms of thrombocytopenia may develop in children, but rarely do so in adults. Examples include Von Willebrand disease type 2 and Fanconi syndrome.
  • Nutritional deficiencies: Vitamin B12, folate, and copper deficiencies are all linked to low platelet counts.
  • Aplastic anemia: Also called bone marrow failure, aplastic anemia occurs when your bone marrow can no longer produce new blood cells, including platelets. A blood transfusion or bone marrow transplant may be required.
  • Spleen issues: While the spleen is responsible for storing platelets, it can sometimes store too many of them, leading to a lower platelet count in your bloodstream. This may be treated with spleen removal (splenectomy), which is also a second-line treatment for primary ITP.

Medical conditions that affect a high platelet count

A high platelet count can lead to the formation of blood clots in your blood vessels. These can stop the normal flow of blood and can lead to potentially life-threatening complications like heart attack or stroke.

Secondary thrombocytosis describes a high platelet count caused by certain medical conditions, such as:

  • Infections: These include chronic infections like tuberculosis, as well as acute bacterial or viral infections. Treating the underlying infection may help normalize platelet counts.
  • Medications: Possibilities include certain antibiotics and cancer drugs. Discontinuing the suspected medication can help address high platelet counts.
  • Inflammatory diseases: RA, sarcoidosis, and inflammatory bowel disease (IBD) are all examples. Treating the underlying condition will help normalize platelet levels.
  • Iron deficiency anemia: Restoring iron levels is a first step in addressing this condition, and it may also help lower high platelet levels.
  • Cancer: Thrombocytosis is associated with several cancers, including those in the blood, colon, and abdominal area.

If you are at risk of blood clots, a doctor might recommend antiplatelet medications, such as anagrelide (Agrylin) to help decrease your platelets.

The symptoms associated with a platelet-related health condition can depend on whether you have low or high platelet counts.

  • easy bleeding from your gums, nose, or small injuries
  • easy bruising
  • blood in your urine or stool
  • vomiting blood
  • small, flat spots underneath your skin that may be red, brown, or purple, depending on skin tone (petechiae)
  • spots from bleeding in your skin (purpura)
  • heavy menstruation
  • extreme fatigue
  • weakness
  • splenic or liver enlargement

A high platelet count can also sometimes cause excess blood clotting, as well as liver or splenic enlargement. Other possible signs and symptoms may include:

  • headaches
  • unexplained tiredness
  • dizziness
  • extreme weakness
  • chest pain
  • heart palpitations
  • swelling or pain in your legs
  • breathing difficulties
  • vision changes
  • slurred speech

A platelet count is measured as part of a complete blood count (CBC), which also measures your red and white blood cell counts.

Sometimes, in addition to the number of cells, a doctor will also order additional lab testing to get a better look at the size and shape of your platelets to help make a more accurate diagnosis. This is called a peripheral blood smear, and is done with a microscopic examination.

A platelet count of less than 20,000 per microliter is considered severely low, and potentially dangerous. However, any platelet count lower than 150,000 or higher than 450,000 per microliter may be considered serious.

A low platelet count is typically treated with medications. For example, primary ITP may be treated with immunosuppressants that prevent your immune system from attacking and destroying platelets in the bone marrow.

Regardless of the exact cause of thrombocytopenia, any significant bleeding that occurs with this condition will likely be treated with a blood transfusion.

You may also consider avoiding certain lifestyle habits that might worsen thrombocytopenia, such as smoking and drinking alcohol.

Platelet-rich plasma (PRP) is a type of injectable treatment touted for a variety of purposes, including injuries and dermatological conditions. It’s made from your own blood, where the process of centrifugation increase the platelet count up to 5 to 10 times.

PRP was previously used for platelet disorders, such as thrombocytopenia. With that said, PRP is primarily coveted for its proteins as a therapeutic procedure, and not as a first-line treatment for low platelet counts. PRP is different from a blood transfusion.

Along with red and white blood cells, platelets make up an important part of your blood. These small cells are the byproducts of large bone marrow cells, and can help stop bleeding from minor injuries.

Due to their role in forming blood clots and preventing internal bleeding, it’s important that you have the right number of platelets. An abnormally low or high platelet count can develop due to inherited or acquired medical conditions, as well as certain medications.

If a doctor suspects a platelet disorder, they will run a CBC test to determine your current platelet counts. The result will help determine any further diagnostic testing and treatment.

Consider contacting a healthcare professional if you’re experiencing possible symptoms of a platelet disorder, such as unexplained bruising or excessive bleeding.