Platelets are small, disk-shaped cells in the blood that help to form blood clots. Thrombocytopenia, the condition of having low platelet numbers in the blood, can occur for a number of reasons and may lead to increased bleeding. Contact your medical professional immediately if you experience unusual, prolonged bleeding or bruising.
Autoimmune Reactions
A number of autoimmune reactions can cause the body to treat platelets as an "enemy" and eliminate them from the blood stream. Such losses of platelets can lead to increased bleeding or internal bleeding. The Mayo Clinic describes several instances of autoimmunity leading to low platelet counts. Idiopathic thrombocytopenic purpura (ITP) is one such autoimmune condition in which the immune system eliminates platelets, resulting in thrombocytopenia. Certain infections can lead to immune responses that cause platelet numbers to drop. Side effects of certain medications can also alter immune function to lead to thrombocytopenia.
Thrombotic Thrombocytopenic Purpura (TTP)
The Mayo Clinic lists thrombotic thrombocytopenic purpura (TTP) as a rare condition in which miniature clots form throughout the body. TTP causes a large number of platelets to be used up in clots, lowers platelet availability in the blood, and results in thrombocytopenia and increased bleeding.
Enlarged Spleen
The spleen is a small, fist-sized organ found in the abdomen that plays an important role in clearing the blood of foreign material. When the spleen becomes enlarged during infection or certain liver disorders, it can trap platelets. According to the National Heart, Lung and Blood Institute, the trapping of platelets in the spleen can lower platelet numbers in the blood.
Effects on Bone Marrow
Like other blood cells, platelets are produced by the bone marrow. Medical conditions that impact the bone marrow can have an effect on platelet production. The National Institutes of Health explain how leukemia and other cancers are often associated with thrombocytopenia and increased bruising and bleeding. Exposure to certain chemicals as well as certain prescription drugs can also lower platelet production through effects on the bone marrow. The Mayo Clinic notes that excessive alcohol can also lower the production of platelets by bone marrow.
