Thrombocytes thrombocytopenia

MANAGING HONE MARROW SUPPRESSION. Bone marrow suppression is a potentially dangerous adverse reaction resulting in decreased production of blood cells. Bone marrow suppression is manifested by abnormal laboratory test results and clinical evidence of leukopenia, thrombocytopenia, or anemia For example, there is a decrease in the white blood cells or leukocytes (leukopenia), a decrease in the thrombocytes (thrombocytopenia), and a decrease in the red blood cells, resulting in anemia Fhtients with leukopenia have a decreased resistance to infection, and the nurse must monitor them closely for any signs of infection. 

In addition to erythrocytes, blood contains white blood cells, called leukocytes, of several types, and platelets, also called thrombocytes, which control blood clotting. Hematopoiesis (from the Greek, haimo, for blood, and poiein for to make ) is the process by which the elements of the blood are formed. The marrow of bone contains so-called stem cells which are immature predecessors of these three types of blood cells. Chemicals that are toxic to bone marrow can lead to anemia (decreased levels of erythrocytes), leukopenia (decreased numbers of leukocytes), or thrombocytopenia. Pancytopenia, a severe form of poisoning, refers to the reduction in circulatory levels of all three elements of the blood. One or more of these conditions can result from sufficiently intense exposure to chemicals such as benzene, arsenic, the explosive trinitrotoluene (TNT), gold, certain drugs, and ionizing radiation. Health consequences can range... 

Medicinal thrombocytopenia can emerge under the use of different medicines, including interferon. The main mechanism of medicinal thrombocytopenia pathogenesis is assisted by the destruction of thrombocytes by the complement which is activated during antibody preparation. On withdrawal, the content of thrombocytes in blood is normalized. The formation of antibodies to thrombocytes in patients with viral hepatitis C occurs due to the destruction of membrane glycoproteins by the viruses. 

Quinidine Quinidine, molecular formula C20H24N2O2, is a stereoisomer of quinine found in Cinchona bark. Chemically, it is known as (2-ethenyl-4-azabicyclo[2.2.2]oct-5-yl)-(6-methoxyquinolin-4-yl)-methanol, or 6 -methoxycinchonan-9-ol. It is used as a Class 1 anti-arrhythmic agent. Intravenous injection of quinidine is also used in the treatment of P. falciparum malaria. Among the adverse effects, quinidine induces thrombocytopenia (low platelet counts) and may lead to thrombocytic purpurea. 

Yamada T, Shinohara K, Katsuki K. Severe thrombocytopenia caused by simvastatin in which thrombocyte recovery was initiated after severe bacterial infection. Clin Drug Invest 1998 16 172-4. 

Thrombocytopenia may be caused by various metabolic disturbances (i.) synthesis disorders (e.g. medicaments, alcohol, folic acid deficiency), (2.) replacement disorders (e.g. immunologically derived degradation, consumption coagulopathy, loss of blood), and (3.) distribution disorders (e.g. increased sequestration in the enlarged spleen, involving up to 90% of the thrombocytes). 

The development of platelets or thrombocytes takes place chiefly in the bone marrow from primitive totipotential reticulum or stem cells. The normal concentration of thrombocytes in the peripheral circulation of the adult is approximately 250,000-355,000/mm . Thrombocyte activity is necessary in the process of coagulation. Quantitative platelet deficiency or thrombocytopenia is one of the most common causes of hemorrhagic diathesis, and it may be due either to decreased platelet production or to increased platelet destruction. 

Reports on the alteration of serum and/or plasma acid phosphatase activity in thrombocytopenia have not always been consistent. Zucker and Woodard (Z2) described a series of 12 patients with thrombocyte-... 

The relation between the toxicity and pharmacokinetics of flucjdosine has been investigated in a retrospective study in 53 patients in an intensive care unit (17). Thrombocjdopenia, as a marker of bone marrow depression, was associated with a reduced clearance of flucytosine the lowest thrombocyte count was linearly related to the clearance of flucytosine. Patients with flucytosine concentrations over 100 pg/ml were at higher risk of thrombocytopenia and raised hepatic transaminases than those who did not exceed this threshold. In a second study, the authors corroborated their earlier findings and showed a significant relation between the lowest thrombocyte counts and thrombocyte counts predicted on the basis of the creatinine clearance in a new set of patients admitted to the intensive care unit (18). 

Thrombocytopenia. Abnormal decrease in the number of thrombocytes below normal values. Frequently detected in patients with autoimmune diseases (e.g. systemic lupus erythematosus, -Sjogren syndrome, mixed connective tissue disease, antiphospholipid syndrome). Primary forms may be drug induced ( - heparin-induced thrombocytopenia) or mediated by antiplatelet antibodies ( - idiopathic thrombocytopenic purpura). 

Patients with leukemia experience a variety of hemorrhagic (bleeding) manifestations caused by a decreased number of platelets. Platelets are small cells that initiate clot formation at the site of endothelial injury. Because of the uncontrolled proliferation of white cells within the limited space of the marrow, the normal platelet precursor cells (the megakaryocytes) in the marrow are "squeezed" or crowded and fail to develop into mature platelets. Consequently, the number of mature platelets (thrombocytes) in the circulation falls, and a thrombocytopenia develops. Because there are fewer platelets to contribute to clot formation, bleeding problems are common. 

The thrombocyte agglutination test in vitro is a diagnostic measure in cases of thrombocytopenia after administration of sulfones. 

As well as erythrocytes, other cells including platelets (thrombocytes) and some hanatopoietic precursor cells can be affected by drag-induced type II hypersensitivity reactions. Drag-induced thrombocytopenia for example is increasing as more drags are released and used. A number of different mechanisms appear to be involved. Drugs may bind covalently to the platelet mem-... 

A man with pulmonary sarcoidosis developed purpura and thrombocytopenia 7 days after routine fluorescein angiography with 10 ml of 5% fluorescein sodium. The patient recovered. When thrombocyte counts were performed before and 2 weeks after fluorescein angiography in 29 clinical subjects, a marked decrease in thrombocytes was observed in 2 subjects. 

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