Platelet count formation

Thrombocytopenia is characterized by a decrease in the platelet count (<100,000/mm3). The nurse monitors patients with thrombocytopenia for bleeding tendencies and takes precautions to prevent bleeding. Injections are avoided but, if necessary, the nurse applies pressure to the injection site for 3 to 5 minutes to prevent bleeding into the tissue and the formation of a hematoma The nurse informs the patient to avoid the use of electric razors, nail trimmers, dental floss, firm... 

Thrombotic thrombocytopenic purpura Condition characterized by formation of small clots within the circulation resulting in the consumption of platelets and a low platelet count. 

White clot syndrome - Rarely, patients may develop new thrombus formation in association with thrombocytopenia resulting from irreversible aggregation of platelets induced by heparin, the so-called white clot syndrome. The process may lead to severe thromboembolic complications. Monitor platelet counts before and during therapy. If significant thrombocytopenia occurs, immediately... 

Platelets, small cell fragments produced from bone marrow cells, work with the cascade of proteins in the formation of blood clots. If platelet counts are low, leaks in blood vessels that would normally be small can lead to the loss of large amoimts of blood. Certain chemotherapy drugs knock out the production of the cells that produce platelets. Oprelvekin (Neumega ), produced in E. coli, stimulates bone marrow to produce that very important type of cell. 

While confirming the general normality of the mutant mice and problems with lymphocyte homeostasis, these studies focused on identifying defects in peripheral leukocytes. The Lsc- - mice had a twofold increase in circulating neutrophils and lymphocytes but normal platelet counts and red blood cells. In functional studies, the Lsc-/ neutrophils showed a reduced ability to stimulate formation of Rho-GTP and abnormal pseudopod development in response to fMLP. An increased motility and lower adherence of the neutrophils when stimulated with fMLP (Francis et ah, 2006) are similar to the behavior of B cells from Lsc / mice when stimulated with serum (Girkontaite et ah, 2001). While these studies imply a role for a G12/i3 Lsc-RhoA pathway in the phenotypes of these cells, the molecular details are not yet known. 

The term myeloproliferative disorders has been applied to all those conditions which are characterized by proliferation of cells in bone marrow or in other sites of extramedullary blood formation. The overgrowth is self-perpetuating and involves one or more lines of bone marrow elements (myelocytic, erythrocytic, megakaryocytic) and cells like fibroblasts derived from the reticulum. We have already mentioned some of these conditions, for example, chronic granulocytic leukemia and myeloid metaplasia, in connection with our discussion on the relationship between serum acid phosphatase and the platelet count. 

The second type of heparin-induced thrombocytopenia is severe and may be associated with a platelet count below 100,000/mm and thrombosis. ° ° The platelet count generally begins to decline 5 to 10 days after the start of heparin therapy (sooner in patients previously treated with heparin). Thrombocytopenia and thrombosis may develop with low-dose heparin, heparin-coated catheters, or even heparin flushes. Historically, the reaction was thought to be mediated by the formation of antibodies to the platelet-heparin complex. However, evidence suggests a complex interaction between heparin, platelet factor 4 (PF4), platelet membrane Fc receptors, and possibly heparin-like molecules on the surface of endothehal cells (Fig. 102-6). Circulating heparin reacts with PF4 to produce a... 

G-CSF and GM-CSF have also proved to be effective in treating the neutropenia associated with congenital neutropenia, cyclic neutropenia, myelodysplasia, and aplastic anemia. Many patients with these disorders respond with a prompt and sometimes dramatic increase in neutrophil count. In some cases, this results in a decrease in the frequency of infections. Because neither G-CSF nor GM-CSF stimulates the formation of erythrocytes and platelets, they are sometimes combined with other growth factors for treatment of pancytopenia. 

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