Low platelet count, or thrombocytopenia, is caused by such conditions as an enlarged spleen, which may trap too many platelets and remove them from blood circulation; bone marrow destruction due to cancer and its treatment; and exposure to toxic chemicals, according to Mayo Clinic. Some anemias also reduce platelet count.
Other conditions cause increased breakdown of platelets in circulation, states Mayo Clinic. Autoimmune disorders, bacterial infections in the blood, hemolytic uremic syndrome and thrombotic thrombocytopenic purpura are examples of illnesses that fall into this category.
Platelets clump together and cause the blood to clot, explains Healthline. Low platelet counts put a patient at risk for bleeding, which may be mild or severe, depending on the underlying cause. Symptoms of low platelet counts include easy bleeding and bruising, a rash that looks like pinpricks of red or purple dots, nosebleeds and bleeding gums, blood in the urine or stools and for women, heavy menstrual periods. In the most serious cases, internal bleeding may result.
Low platelet counts are commonly diagnosed with blood tests such as a complete blood count and a blood smear, according to the National Heart, Lung, and Blood Institute. Bone marrow aspiration and biopsy may also be used to determine whether or not the bone marrow is healthy and producing platelets properly.
Treatments for low platelet counts include medications such as corticosteroids that slow platelet destruction, or rituximab and immunoglobulins that reduce the activity of the immune system, states the National Heart, Lung, and Blood Institute. Blood or platelet transfusions may also be used when there is active bleeding.