Thrombocytopenia is an abnormally low level of platelets in the blood. Platelets are made by the bone marrow, and they help your blood to clot. People with thrombocytopenia can have excessive bleeding.

Most people have more than 150,000 platelets per microliter of blood. Anyone with fewer platelets has some degree of thrombocytopenia. The risk of bleeding increases as the platelet count decreases, so people with less than 10,000 platelets per microliter of blood are at high risk of severe bleeding.

Thrombocytopenia can occur alone, or it can develop as a complication of another disease, such as cancer or a viral infection. In some cases, thrombocytopenia is a chronic (long-lasting) condition that persists for years, but in other cases, it develops suddenly and dramatically.

In general, thrombocytopenia develops because of one or more of the following reasons:

• The body's bone marrow fails to produce enough platelets. This can happen because:



• A cancer, such as leukemia or lymphoma, gets into the bone marrow and destroys megakaryocytes, the cells that produce platelets.
• Aplastic anemia affects platelet production.
• A toxic chemical, radiation therapy or chemotherapy destroys megakaryocytes.
• Genetic problems, such as Wiskott-Aldrich syndrome or May-Hegglin anomaly, hinder production of normal platelets.
• Exposure to certain drugs, especially thiazide diuretics or alcohol, slows the production of megakaryocytes. Because drinking large amounts of alcohol can seriously slow platelet production, transient thrombocytopenia is a common syndrome in heavy drinkers, especially if the drinker's diet is low in iron, vitamin B12 or folate.
• After suffering from a viral infection, such as chicken pox, parvovirus, mumps, rubella or Epstein-Barr virus, some patients will have decreased platelet production. This problem is usually short term and improves without treatment.


• The bone marrow produces enough platelets, but the body destroys them. Some common causes of this problem include:



• Immune thrombocytopenic purpura (ITP) � This condition can pass quickly or can last a long time.
• Autoimmune diseases � These include systemic lupus erythematosus (SLE), polyarteritis and dermatomyositis.
• AIDS � People with AIDS often develop thrombocytopenia before other symptoms.
• Complications of pregnancy � About 5% of pregnant women develop mild thrombocytopenia when they are close to delivery.
• A reaction to a medication � Thrombocytopenia can be caused by any medication, but it occurs somewhat frequently from taking valproic acid (Depakote), gold salts, heparin (Calciparine, Liquaemin) and several other medications. For example, up to 15% of hospitalized patients who receive heparin to prevent blood clots eventually develop thrombocytopenia. In most cases, thrombocytopenia develops within two to five days of starting a new drug.
• Physical trauma � Platelets can be injured or destroyed as they pass through an artificial heart valve, through a blood vessel graft, or through the machines and tubing used in massive blood transfusions or cardiopulmonary bypass surgery.
• Infections � Thrombocytopenia can develop after such infections as mononucleosis or cytomegalovirus.
• Thrombotic thrombocytopenic purpura (TTP) � This is a rare disease that causes low levels of platelets, along with a variety of other symptoms and complications.


• Too many platelets remain in the spleen. Normally, about one-third of your platelets are in your spleen and the rest are circulating in your blood. However, if the spleen gets larger because of severe liver disease (especially cirrhosis), Gaucher's disease or cancer, it can begin to hoard too many platelets. This leaves fewer platelets to circulate in your bloodstream, causing thrombocytopenia.

People with severe thrombocytopenia may have abnormal bleeding almost anywhere in the body. Symptoms can include:

• Reddish or purplish spots in the skin, often concentrated in the lower legs
• Excessive bruising, even from minor trauma
• Blood in the urine or stool
• Abnormal or excessive bleeding from the mouth or nose, especially nosebleeds or bleeding when you brush your teeth
• Abnormal vaginal bleeding, especially unusually heavy menstrual flow
• Bleeding inside the gastrointestinal tract, including bleeding from the rectum
• Excessive bleeding after surgery or dental work
• Headache and other neurological symptoms caused by bleeding inside the brain (brain hemorrhage). This is extremely rare.

Your doctor will begin by asking you about your medical history. He or she will ask whether you recently have had any medical procedures or received any blood transfusions and whether you are taking any medications (including over-the-counter and herbal remedies). Your doctor also may ask about how much alcohol you drink and your diet. You also will be asked questions to determine whether you are at risk of AIDS, including questions about where and when you've had blood transfusions, your sexual practices, whether you have ever used intravenous drugs, and whether you could have been exposed to infectious blood or bodily fluids at work. If you are pregnant, your physician will want to know your due date. Your doctor also will ask you if you have had any recent infections or vaccinations, if you have any achy joints or rashes, and if anyone in your family has ever had low platelets levels.

Your doctor will examine you for specific signs of abnormal bleeding, such as bruises or blood spots in your skin. He or she also will feel your abdomen to determine whether your spleen is enlarged and will look for any signs of liver disease, such as a yellowing of the skin and eyes (jaundice).

To confirm the diagnosis of thrombocytopenia, your doctor will order a blood test to measure the number of platelets in your blood (a platelet count). Your doctor also will look at your blood under a microscope.

Once your doctor has determined that you have thrombocytopenia, the next step is to find the cause. If your doctor thinks you may be having a reaction to a drug, he or she may ask you to stop taking the medication to see if your platelet count rises. If that happens, you have drug-induced thrombocytopenia.

In many cases, your doctor will need to do a bone marrow biopsy. In this procedure, a long needle is used to remove a small piece of bone marrow that can be examined in a laboratory. The appearance of your bone marrow and your megakaryocytes (platelet-producing cells) will help to determine what is causing your problem.

How long thrombocytopenia lasts depends on its cause. For example, some patients with chronic ITP experience years of easy bruising and abnormally heavy vaginal bleeding, with repeated episodes of more severe bleeding. Others have such mild thrombocytopenia that they almost never have noticeable bleeding problems. Many people with drug-induced thrombocytopenia recover within 7 to 10 days after they stop taking the medication. Most children with acute ITP recover within 4 to 6 weeks.

Many cases of thrombocytopenia cannot be prevented. You can avoid drinking large amounts of alcohol to lower your risk of developing thrombocytopenia caused by heavy drinking.

If you already have had one episode of drug-induced thrombocytopenia, there is a good chance the problem will return if you take the same medication again. To help prevent this, be sure to record the name of the specific medication that caused the problem. Tell every health care professional that you visit about your sensitivity to this drug.

If your doctor has determined that you are at risk of developing thrombocytopenia, he or she may tell you not to take aspirin because it impairs platelet function.

How thrombocytopenia is treated depends on its cause and how severe it is. If your thrombocytopenia is mild and is not causing any significant bleeding, your doctor may decide you do not need treatment. This is often the standard strategy in children with acute ITP, because 80% to 90% of these children recover without treatment within 6 weeks. If your thrombocytopenia is drug induced, your physician may change your prescription. Most people with drug-induced thrombocytopenia recover without additional treatment after they stop taking the medication.

Patients with more significant bleeding will need more aggressive treatment. Options for treatment include:

• Medications called glucocorticoids taken intravenously or by mouth or a medication called immunoglobulin given through a needle into a vein (intravenously) � This is done to treat thrombocytopenia caused by an abnormal immune reaction.



• Platelet transfusions � Transfusions of platelets usually are reserved for patients with thrombocytopenia and active bleeding or a high risk of bleeding.



• Splenectomy (surgical removal of the spleen) � This is done most commonly to treat ITP that has not improved with other treatment. If the spleen is removed, thrombocytopenia goes away in as many as 60% of patients with ITP. If removing the spleen doesn't help, then immunosuppressive drugs may be given, including azathioprine (Imuran), cyclophosphamide (Cytoxan, Neosar), vincristine (Oncovin and others) or vinblastine (Velban).

Call your doctor if you develop any of the symptoms of thrombocytopenia, especially if you notice abnormal bruises or if you experience significant bleeding from your nose, mouth, vagina, rectum or urinary tract.

Episodes of thrombocytopenia can be life threatening, especially if the bleeding is severe or if it involves the brain. However, the overall outlook is generally good, especially if the cause can be identified and removed. Long-term management of the condition is often successful.

National Heart, Lung, and Blood Institute (NHLBI)
P.O. Box 30105
Bethesda, MD 20824-0105
Phone: 301-592-8573
TTY: 240-629-3255
Email: nhlbiinfo@rover.nhlbi.nih.gov
http://www.nhlbi.nih.gov/