Idiopathic thrombocytopenic purpura (ITP) is the condition of having a short platelet count of no known cause. As most causes appear to be associated to antibodies against platelets, ITP is also recognized as immune thrombocytopenic purpura or immune-mediated thrombocytopenic purpura. Often ITP is asymptomatic, however a very little platelet count can lead to visible symptoms, such as purpura, or more seriously, bleeding diathesis. In many cases, ITP's cause is not idiopathic but autoimmune, with antibodies beside platelets being detected in approximately 60 percent of patients. Most often these antibodies are against platelet covering glycoproteins IIb-IIIa or Ib-IX, and are of the IgG type. The famous Harrington Hollingsworth experiment recognized the immune pathogenesis of ITP.
The covering of platelets with IgG renders them liable to opsonization and phagocytosis by splenic macrophages. The IgG autoantibodies are also thought to injure megakaryocytes, the precursor cells to platelets, but this is thought to contribute only slightly to the reduce in platelet numbers. The stimulus for auto-antibody making in ITP is probably abnormal T cell activity Preliminary findings suggest that these T cells can be influenced by drugs that target B cells, such as rituximab. The diagnosis of ITP is a procedure of exclusion. First, the clinician has to determine that there are no blood abnormalities other than small platelet count, and no physical signs except for signs of bleeding. Then, the secondary reason should be excluded. Secondary causes could be leukemia, medications, lupus erythematosus, cirrhosis, HIV, hepatitis C, inborn causes, and others.
In approximately one percent of cases, autoimmune hemolytic anemia and ITP coexist, a state referred to as Evans syndrome. A platelet count below 20,000 is usually an indication for treatment. Patients with a count between 20,000 and 50,000 are usually estimated on a case-by-case basis, and, with rare exceptions, there is usually no need to treat patients with a count above 50,000. Hospitalization may be recommended in cases of very low counts, and is highly desirable if the patient presents with significant internal or mucocutaneous bleeding. A count below 10,000 is potentially a medical emergency, as the patient may be susceptible to subarachnoid or intracerebral hemorrhage as a result of moderate head trauma. In most cases, treatment will be administered under the way of a hematologist.
useful links : transport rankings
The covering of platelets with IgG renders them liable to opsonization and phagocytosis by splenic macrophages. The IgG autoantibodies are also thought to injure megakaryocytes, the precursor cells to platelets, but this is thought to contribute only slightly to the reduce in platelet numbers. The stimulus for auto-antibody making in ITP is probably abnormal T cell activity Preliminary findings suggest that these T cells can be influenced by drugs that target B cells, such as rituximab. The diagnosis of ITP is a procedure of exclusion. First, the clinician has to determine that there are no blood abnormalities other than small platelet count, and no physical signs except for signs of bleeding. Then, the secondary reason should be excluded. Secondary causes could be leukemia, medications, lupus erythematosus, cirrhosis, HIV, hepatitis C, inborn causes, and others.
In approximately one percent of cases, autoimmune hemolytic anemia and ITP coexist, a state referred to as Evans syndrome. A platelet count below 20,000 is usually an indication for treatment. Patients with a count between 20,000 and 50,000 are usually estimated on a case-by-case basis, and, with rare exceptions, there is usually no need to treat patients with a count above 50,000. Hospitalization may be recommended in cases of very low counts, and is highly desirable if the patient presents with significant internal or mucocutaneous bleeding. A count below 10,000 is potentially a medical emergency, as the patient may be susceptible to subarachnoid or intracerebral hemorrhage as a result of moderate head trauma. In most cases, treatment will be administered under the way of a hematologist.
useful links : transport rankings
No comments:
Post a Comment