Thrombocytopenia 101: Simple Answers to Basic Questions

Thrombocytopenia (a.k.a. thrombopenia) is the medical term that describes a low platelet count, i.e. a deficiency of platelets in the bloodstream. The term thrombocytopenia derives from the Greek words thrombocyte (= platelet) and penia (= lack, dearth, deficiency). Thrombocyte literally means "clotting cell" (from the Greek thrombos, clot, and -cyte, cell)

2) What are platelets?

Platelets (thrombocytes) are tiny cellular blood components that help blood to clot. What is more, platelets are the body's first line of defense against bleeding (primary hemostasis). If you sustain a cut, however small, platelets rush to the site of the injury (platelet aggregation), clump together (platelet adhesion) and form a clot, a scab (platelet activation and formation of the platelet hemostatic plug).

3) Where are platelets produced?

Platelets (as well as red blood cells and white blood cells) are produced in the bone marrow. Once released in the bloodstream, platelets have an average life-span of 10 days.

4) What is a normal platelet count?

A normal platelet count ranges from 150,000 to 450,000 per mm³.

5) What is a low platelet count?

A platelet count under 80,000 per mm³ is considered low. A count under 20,000 per mm³ is very low and can be life-threatening as it can trigger massive bleeding.

6) What causes thrombocytopenia?

Platelets are produced in the marrow, released into the circulating blood, and destroyed in the spleen. Anything that interferes with any stage of the life-cycle of platelets can cause thrombocytopenia. For example, certain cancers and cancer therapies (leukemia, chemotherapy, radiation) can affect the bone marrow and decrease the production of platelets. In other cases, the body's immune system mistakes platelets for foreign cells and destroys them (autoimmune diseases). Some disorders cause the spleen to enlarge (splenomegaly). The enlarged spleen traps (sequesters) an excessive number of platelets and, in doing so, depletes the circulating blood of platelets. Certain antibiotics, anticoagulants (heparin), and diabetes drugs can cause a low platelet count. Excessive alcohol consumption is also a risk factor for thrombocytopenia.

7) What are the symptoms of thrombocytopenia?

When the thrombocytopenia is very mild, there can be no symptoms (asymptomatic thrombocytopenia). If the platelet count drops under 100,000 per mm³, there may be spontaneous bleeding from the nose and gums, blood in the urine and/or stools, unusually heavy menstruation, abnormal bruising, and petechiae (tiny little reddish marks on the skin, resembling a rash).

8) How is thrombocytopenia diagnosed?

A platelet count test is performed as part of a CBC (complete blood count) in your yearly checkup. If the platelet count is low, the doctor may ask for more tests (e.g. clotting times, bone marrow biopsy) to diagnose the underlying condition that is causing the platelet deficiency.

9) How is thrombocytopenia treated?

It isn't so much the thrombocytopenia per se that is treated, but the underlying disorder that is triggering it. Severe bleeding will warrant platelet transfusions. If the platelet deficiency is drug-induced, the doctor will discontinue the medication in question. Splenectomy (surgical removal of the spleen) may be done when all other therapeutic approaches have failed. It is estimated that the platelet count can go up as much as 30% after a splenectomy.