Thrombocytopenia: Causes, Symptoms, Diagnosis and Treatment

Thrombocytopenia means that the number of platelets in the blood is lower than normal. Platelets are blood cells produced in the bone marrow that help form clots and stop bleeding. A low platelet count may cause no symptoms, or it may increase the risk of bruising and bleeding.

This article provides general health information and does not replace an examination, diagnosis or treatment plan from a qualified healthcare professional.

When urgent medical help is needed

Seek urgent medical care for bleeding that does not stop, blood in vomit, urine or stool, a sudden severe headache, confusion, weakness, a significant head injury, or rapidly spreading bruising or pinpoint red spots. Severe thrombocytopenia can cause dangerous internal bleeding.

Common symptoms

Mild thrombocytopenia is often found during a routine blood test and may not cause noticeable symptoms. When symptoms occur, they can include:

• easy or unexplained bruising;
• petechiae — small red, purple or brown spots under the skin;
• purpura — larger areas of bleeding under the skin;
• frequent nosebleeds or bleeding gums;
• bleeding that lasts longer than expected after a minor injury;
• heavy menstrual bleeding;
• blood in urine or stool.

Why platelet counts can fall

Thrombocytopenia can be inherited or acquired. The main mechanisms are reduced platelet production, increased destruction or use of platelets, and sequestration of too many platelets in an enlarged spleen.

Reduced production

The bone marrow may not produce enough platelets because of aplastic anemia, leukemia or lymphoma, certain infections, nutritional deficiencies, chemotherapy, radiation therapy, alcohol exposure or other bone-marrow disorders.

Increased destruction or consumption

The immune system may mistakenly destroy platelets, as in immune thrombocytopenia. Some medicines can trigger thrombocytopenia. Platelets may also be consumed rapidly in serious conditions such as disseminated intravascular coagulation or thrombotic thrombocytopenic purpura.

Enlarged spleen and other causes

An enlarged spleen can store more platelets than usual and reduce the number circulating in the blood. Liver disease, pregnancy, severe infection, surgery and several other medical conditions can also affect platelet counts.

How thrombocytopenia is diagnosed

Diagnosis starts with medical and family history, symptoms, medicines and supplements, and a physical examination for signs of bleeding or an enlarged spleen. Tests may include:

• a complete blood count to measure platelets and other blood cells;
• a peripheral blood smear to examine the cells under a microscope;
• repeat testing to exclude a laboratory counting error;
• blood tests for suspected infections, immune disorders, liver disease or clotting abnormalities;
• bone marrow testing when a disorder of blood-cell production is suspected.

A platelet number alone does not establish the cause or the individual risk of bleeding. Results must be interpreted together with symptoms, other blood counts, medical history and current treatment.

Treatment

Treatment depends on the cause, the platelet count, symptoms and the risk of bleeding. Mild cases may only need observation and repeat blood tests. When treatment is required, a clinician may address the underlying illness, review medicines that affect platelets, use medicines that modify the immune response or stimulate platelet production, or recommend other specialist treatment.

Platelet transfusion may be used for severe bleeding or in specific high-risk situations. Some patients with immune thrombocytopenia may require corticosteroids, immunoglobulin therapy, other immune-directed medicines or, less commonly, removal of the spleen. These decisions require individualized medical assessment.

Everyday safety

• Tell doctors, dentists and pharmacists about a low platelet count.
• Ask a clinician before using aspirin, ibuprofen, anticoagulants, supplements or other products that may increase bleeding.
• Do not stop a prescribed medicine without medical advice.
• Discuss sports, work and travel restrictions if the platelet count is very low.
• Keep scheduled blood tests and seek help if bleeding symptoms appear or worsen.

Sources and further reading

• National Heart, Lung, and Blood Institute: Thrombocytopenia
• MedlinePlus: Platelet Disorders
• MedlinePlus: Platelet Tests

Last reviewed for this informational archive: August 2026.