Plateletopenia - Causes and Symptoms

Definition

The term thrombocytopenia (or thrombocytopenia) indicates a quantity of circulating platelets less than 150, 000 units per mm3 (microliter) of blood (the platelet count is normally between 150, 000 and 400, 000 / mm3). The threshold below which hemostasis changes begin to occur is 50, 000 / mm3. The number of platelets in the blood can vary slightly depending on the phases of the menstrual cycle, decreases in the later stages of pregnancy (gestational thrombocytopenia) and increases in response to inflammatory cytokines (secondary or reactive thrombocytosis). Decreased platelets, like other platelet dysfunctions, can cause defects in blood coagulation and hemorrhagic manifestations of various types (note: the risk of bleeding is inversely proportional to the platelet count). Symptoms related to reduced platelet counts include petechiae, purpura and mucosal bleeding. The causes of thrombocytopenia can be classified on the basis of the pathophysiological mechanism that determines them and include reduced production, increased destruction at splenic level or consumption (both immune, and non-immune), dilution (for example, for blood transfusions massive) and the association of these processes. Platelet disorders can be primitive (or idiopathic) when the triggering cause is not known (eg idiopathic thrombocytopenic purpura). Often, thrombocytopenia can also be observed when the marrow is affected by infectious, inflammatory or neoplastic processes, such as in the case of leukemias, lymphomas, marrow fibrosis, aplastic anemia, lymphoproliferative disorders and some myelodysplastic syndromes. A decrease in platelets, however, can also occur in the course of infectious diseases (eg hepatitis, measles, chickenpox, rubella, mononucleosis, HIV and cytomegalovirus infection), collagen diseases, autoimmune reactions (eg systemic lupus erythematosus) and some processes neoplastic. Other possible causes include: liver cirrhosis (with portal hypertension and increased spleen volume), chronic bleeding problems (eg cerebral haemorrhage, complications of stomach ulcers), Vitamin B12 deficiency or folate, allergies and anaphylactic reactions, burns, sepsis and acute respiratory distress syndrome. Thrombocytopenia can result from the action of various toxic substances (eg alcohol abuse) and drugs (most common: quinine, trimethoprim / sulfamethoxazole and chemotherapeutic agents) that produce dose-dependent myelosuppression or trigger an immune-mediated destruction of platelets.