Mayo Clinic Health Manager
Get free personalized health guidance for you and your family.
Get Started
About our e-newsletters
- Free e-newsletters
- Mayo Clinic expertise
- We do not share your e-mail address
Housecall, our weekly general-interest e-newsletter, keeps you up to date on a wide variety of health topics with timely, reliable, practical information, recipes, blogs, questions and answers with Mayo Clinic experts and more. Our biweekly topic-specific e-newsletters also include blogs, questions and answers with Mayo Clinic experts, and other useful information that will help you manage your health.
Housecall Archives
Mayo Clinic Housecall
Stay up to date on the latest health information.
What you get
- Free weekly e-newsletter
- Mayo Clinic expertise
- Recipes, tools and other helpful information
- We do not share your e-mail address
Causes
By Mayo Clinic staff
Normally, you have anywhere from 150,000 to 450,000 platelets per microliter of circulating blood. Because each platelet lives only about 10 days, your platelet supply is continually renewed by production of new platelets from your bone marrow.
If for any reason your blood platelet count falls below normal, the condition is called thrombocytopenia. Complications may range from none at all to severe bleeding. The risk of bleeding increases as the number of platelets decreases. The greatest risk is when platelet count falls very low — below 10,000 platelets per microliter. At this point, internal bleeding may occur despite a lack of any injury, although this is rare.
Causes of thrombocytopenia generally fall under one of the several categories below.
Reduced production of platelets
Platelets are produced in your bone marrow. A medical problem that involves your bone marrow, such as occurs with leukemia and some types of anemia, could lead to a reduction in the number of new platelets produced. Viral infections, including HIV infection, may suppress your bone marrow's ability to make platelets. Other cancers that affect bone marrow, chemotherapy drugs and heavy alcohol consumption also can impair platelet production.
Increased breakdown of platelets
A number of conditions can cause your body to use up or destroy platelets more rapidly than they are produced, leading to a shortage of platelets in your bloodstream. Examples include:
- Pregnancy, which may cause mild thrombocytopenia.
- Idiopathic thrombocytopenic purpura (ITP), a condition in which your immune system mistakenly identifies platelets as a threat and forms antibodies that attack them.
- Other autoimmune diseases, such as lupus or rheumatoid arthritis, which may lead to destruction of platelets due to a malfunctioning immune system.
- Blood poisoning from severe bacterial infections (bacteremia), which may lead to destruction of platelets.
- Thrombotic thrombocytopenic purpura (TTP), a rare, life-threatening condition that occurs when small blood clots suddenly form throughout your body, using up large numbers of platelets. TTP sometimes happens as a result of a genetic deficiency, but more often the cause is unknown. In some cases, it may be associated with infection or a chronic illness.
- Hemolytic uremic syndrome, another rare disorder that causes a sharp drop in platelets, destruction of red blood cells and impairment of kidney function. Sometimes, this can occur in association with a bacterial Escherichia coli (E. coli) infection, such as may be acquired from eating raw or undercooked meat (often hamburger).
Certain medications can cause a thrombocytopenic reaction by confusing the immune system and causing it to destroy platelets. Examples include heparin, quinidine, quinine, sulfa-containing antibiotics, some oral diabetes drugs, gold salts and rifampin.
In some cases, heparin-induced thrombocytopenia can cause excessive blood clotting instead of bleeding, increasing the risk of clot formation deep within a leg blood vessel or the transport of such a clot to your lungs, which can be life-threatening.
Trapping of platelets in the spleen
The spleen is a small organ about the size of your fist located just below your rib cage on the left side of your abdomen. Normally, your spleen works to fight infection and filter unwanted material from your blood. An enlarged spleen — which can be caused by a number of disorders — may harbor too many platelets, causing a decrease in the number of platelets in circulation.
