Consumptive Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Consumptive and links to relevant pages within the course.
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|Increased platelet destruction|
The most common cause of thrombocytopenia is increased destruction of platelets. Platelets are eliminated from peripheral circulation faster than the bone marrow can produce new platelets.Increased platelet destruction may be the result of immune or nonimmune mechanisms. Immune platelet destruction begins when antibodies coat platelets. These sensitized platelets are then destroyed by macrophages, mostly from the spleen but also from the liver. Disorders that are associated with immune mechanisms of destruction include: Idiopathic (or immune) thrombocytopenic purpura (ITP) Heparin-induced thrombocytopenia (HIT) Neonatal alloimmune thrombocytopenia (NAIT)Increased destruction of platelets is not always caused by the immune system. Platelet destruction can occur as a result of abnormal platelet aggregation or endothelial cell injury. Both of these occurrences can cause fibrin to form in arterioles and capillaries. This leads to platelet activation and consumption. Conditions associated with nonimmune destruction and consumptive thrombocytopenia include: Thrombotic thrombocytopenic purpura (TTP) Hemolytic uremic syndrome (HUS) Disseminated intravascular coagulation (DIC) All of these conditions are associated with significantly decreased platelet counts that may become life threatening. Restoration of platelet numbers is essential to promote clotting and vascular patency.
|Thrombotic Thrombocytopenic Purpura and Hemolytic Uremic Syndrome|
Thrombotic thrombocytopenic purpura (TTP) is an uncommon, but very serious consumptive platelet disorder. Its cause is unknown, but there are several possible precipitating factors including infection, carcinoma, and pregnancy. More women than men are affected by TTP. If left untreated, the mortality rate is in excess of 90% due to multiorgan failure. Hemolytic uremic syndrome (HUS) is also a platelet consumptive disorder. HUS is thought by some to be the same condition as TTP because both disorders have the same underlying pathology. However, HUS is more often associated with renal failure and TTP with neurological manifestations including visual impairment, weakness, headache, dizziness, disorientation. seizures, or coma. Microangiopathic hemolytic anemia, thrombocytopenia, and fever is associated with both TTP and HUS. The patient's condition can deteriorate rapidly while these symptoms are becoming evident. HUS is usually seen in children; it is the most common cause of acute renal failure in children. Patients may have bloody diarrhea and symptoms resembling colitis. Diarrhea-related HUS is usually associated with ingestion of undercooked beef contaminated with Ecoli O157:H7; it is the Shiga-like toxin from this serotype that causes the illness. Some patients may have long term kidney dysfunction as a result ofthis virulent infection. For patients who have experienced renal failure, dialysis may be required.