Thrombocytopenia is a condition caused by low platelet count. Platelets (also known as thrombocytes) help your blood clot, and low levels can lead to easy bruising and bleeding. There are several health conditions that cause thrombocytopenia by encouraging the breakdown of platelets or limiting their production.¹ Thromobcytopena can also be caused by an enlarged spleen sequestering (trapping) platelets inside of itself. Knowing what causes thrombocytopenia and the signs to recognize it can help you get the treatment you need. Untreated cases can lead to health complications and in severe cases, to internal bleeding.

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What Is Thrombocytopenia?

Healthy platelet levels typically range from 150,000 to 400,000 platelets per microliter.² Thrombocytopenia is diagnosed when your platelet levels fall below 150,000 platelets per microliter of blood. This drop interferes with your blood’s ability to clot, which can lead to bleeding on or underneath your skin or internally. Many people don’t notice they have thrombocytopenia until their platelet counts drop very low, causing abnormal bleeding.³

Causes of Thrombocytopenia

Platelets (also known as thrombocytes) are tiny, colorless pieces of cells that help create blood clots. When a blood vessel becomes damaged, platelets stick to the outside of the vessel and release chemicals that recruit other platelets. They all stick together, forming a platelet plug that stops bleeding.⁴ Platelets begin clot formation.Stem cells are specialized cells that have the ability to mature into red blood cells (RBCs), white blood cells (WBCs), or platelets. They reside in the spongy tissue inside your bones, known as bone marrow. Megakaryocytes are specialized cells in bone marrow that are responsible for making platelets. They’re constantly making new platelets to replenish your body’s supply, as platelets only live for around 10 days in your blood.¹

Thrombocytopenia may develop if your megakaryocytes aren’t making enough platelets. Certain types of cancer or medications can affect your bone marrow health, impacting your cells’ function.

Risk Factors for Thrombocytopenia

There are several health conditions and medications that can increase your risk of developing thrombocytopenia. Factors that reduce platelet production include:¹

Viral infections — caused by human immunodeficiency virus (HIV) or hepatitis C
Certain types of blood cancers — such as leukemia (cancer of the bone marrow) or lymphoma (cancer of the lymphatic system)
Cancer treatments — those that kill rapidly dividing cells, such as radiation therapy and chemotherapy
Certain types of anemia — cause low blood cell counts
Heavy alcohol consumption — damages the bone marrow, destroys platelets, and enlarges the spleen
Exposure to certain toxic chemicals — such as benzene (from manufacturing industries), arsenic, or pesticides

Factors that cause your body to break down or use up platelets faster than they’re made include:¹

Severe bacterial infections in your blood — can destroy platelets
Taking certain medications — such as anticonvulsants (seizure medications), heparin (a blood thinner), and some antibiotics
Pregnancy — increases your blood volume, which dilutes circulating platelets
Immune thrombocytopenia — caused by autoimmune diseases such as rheumatoid arthritis or lupus; your immune system recognizes platelets as foreign and destroys them
Thrombotic thrombocytopenic purpura — a rare condition caused by the sudden formation of small blood clots throughout your body that use up your platelets
Hemolytic uremic syndrome — damage to the small blood vessels in your kidneys, which causes blood clots to form, using up your platelets

Another risk factor for developing thrombocytopenia is having an enlarged spleen (splenomegaly). Normally, the spleen filters your blood and helps your body fight infections. When it becomes enlarged, platelets can get trapped, lowering your circulating platelet levels. Conditions that cause splenomegaly include:⁵

Bacterial and viral infections, such as syphilis or mononucleosis
Blood cancers
Autoimmune diseases, such as sarcoidosis or lupus
Malaria infection
Liver diseases, such as cirrhosis
Increased pressure or blood clots in your liver or spleen’s veins

Thrombocytopenia (Low Platelet) Symptoms

Thrombocytopenia interferes with your blood’s ability to form clots. With this, you may notice signs of excess bleeding, such as:³

Frequent nosebleeds
Bleeding from your gums after brushing your teeth
Heavy bleeding during your menstrual cycle
Bleeding for an extended period of time after a small cut or injury
Purpura, or the formation of purple, red, or yellowish-brown spots in your skin
Petechiae, or small, flat red spots that form under the skin from leaky blood vessels
Bloody urine or stools, which may be bright red or dark and tarry in color

These symptoms may appear slowly over time or suddenly. Many people with mild thrombocytopenia don’t notice they have it until they have routine blood work done that shows they have low platelet levels.

How Is Thrombocytopenia Diagnosed?

If you have a risk factor for thrombocytopenia, your doctor may test your platelet levels to ensure they’re within a normal range. Otherwise, doctors don’t screen for high or low platelet counts. Most of the time, thrombocytopenia is caught during a routine blood test known as a complete blood count (CBC). This test measures the levels of different cell types in your blood, which are used to monitor your overall health.²

From there, your case can range from mild to severe based on your platelet counts:

Mild thrombocytopenia: 100,000 to 150,000
Moderate thrombocytopenia: 50,000 to 100,000
Serious thrombocytopenia: Less than 50,000
Severe thrombocytopenia: Less than 20,000

Your doctor may also order a peripheral blood smear test. This test uses a drop of blood that is smeared onto a glass slide and stained with different chemicals. A doctor will be able to see your red blood cells, white blood cells, and platelets under a microscope. If you have fewer platelets, you may have thrombocytopenia. A peripheral blood smear can also look for other cell abnormalities that may point to what’s causing your low platelet levels.⁶

An abdominal ultrasound is used to look for any changes in your spleen, liver, or lymph nodes. This test uses sound waves that bounce off your organs and enter the wand (transducer), creating pictures. An ultrasound can show whether you have splenomegaly, enlarged lymph nodes, or liver damage.⁷

Bone marrow tests check whether your bone marrow is making platelets and other healthy blood cells. Your doctor may order a biopsy or aspiration, which uses a large needle that’s inserted into your bone marrow to remove some cells for viewing under a microscope.⁸

Complications from Thrombocytopenia

If you’re diagnosed with thrombocytopenia, it’s important to take the medications prescribed by your doctor and to watch out for new symptoms of bleeding. If thrombocytopenia isn’t well-managed, it can lead to or complicate other health complications. These include:⁹

Bone marrow failure
Pregnancy complications
Decreased blood flow to your heart, which may result in a heart attack
Leukemia or lymphoma
Blood clots that travel to your extremities (arms and legs), lungs, or brain
Bleeding in your digestive system or brain

Signs of Severe Complications of Thrombocytopenia

Knowing the signs of a heart attack, stroke, and internal bleeding is important when living with thrombocytopenia. These are medical emergencies that need to be treated immediately. If you notice any of the following signs, call 9-1-1 immediately.

Signs of a heart attack include:¹⁰

Chest pain or discomfort that may feel like squeezing or pressure in the center or left side of your chest; it typically lasts for a few minutes and may continue to come and go
Shortness of breath that accompanies chest pain
Pain or discomfort in one or both of your shoulders or arms
Pain or discomfort in your neck, jaw, or back

Signs of a stroke include:¹¹

Sudden slurred speech or difficulty understanding speech
Drooping of one side of your face
Sudden vision loss in one or both eyes
Sudden unexplainable headache
Sudden weakness or numbness on one side of your body in your arms, legs, or face
Sudden difficulties walking or balancing

Signs of a brain bleed include:¹²

Sudden weakness or numbness on one side of your body in your arms, legs, or face
Drooping of one side of your face
Sudden unexplainable headache
Sudden vision loss in one or both eyes
Seizures
Sensitivity to light
Trouble swallowing

Signs of an abdominal bleed include:¹³

Vomiting bright red or dark brown blood that looks similar to coffee grounds
Bloody stools and/or rectal bleeding
Black, tarry stools
Abdominal pain
Chest pain
Lightheadedness or fainting
Breathing difficulties

Resources for Living with Thrombocytopenia

If you or a loved one are living with thrombocytopenia, the Platelet Disorder Support Association (PDSA) offers support resources for those with platelet disorders. These include health insurance and assistance programs, discussion and support groups, and connections with healthcare providers.